Opening cutscenes only play audio in right ear, after those inital cutscenes audio worked perfectly.

gamescope -h 847 -H 1440 -f --backend sdl -F fsr --mangoapp -- %command%
Need to use gamescope as the game would not display correctly with fractional scaling on Gnome

Runs well
I had to disable Steam Input for this game to make my 8BitDo-Controller work, but once this was done, there were no more issues at all.
Other than having to disable Steam Input to make my controller work with the game, there are no issues at all. Can recommend.
Game runs pretty well on my hardware. Had to use the listed launch option to get it to start due to EAC.
env --unset=SDL_VIDEODRIVER %command%

LD_PRELOAD="/usr/lib/libgamemodeauto.so.0" VK_LOADER_LAYERS_ENABLE=VK_LAYER_MANGOHUD_overlay_x86_64 gamemoderun %command%
No issues of note.

MANGOHUD=1 gamemoderun %command%
Supports ultrawide resolution natively.
Launch Options
MANGOHUD=1 → Shows overlay for FPS, frametime, temperatures, etc.
gamemoderun → CPU performance optimizations

Works pretty much right out of the box
For the first ~10 minutes of cutscenes, voices were only in your right ear. After the initial cutscenes, this stopped.
Seems like a fun game now it's gotten some patches. Wish it had launched this way
Had to switch Proton 8.0-5. EAC would crash on 9.0-4 even with Proton EasyAntiCheat Runtime installed
VKD3D_CONFIG=dxr VKD3D_FEATURE_LEVEL=12_2 VKD3D_SHADER_MODEL=6_6 gamemoderun %command%

The tutorials are all difficult to read and it's impossible to read the maps without using the Deck's magnifying lens feature. I didn't notice if too many other UI elements are difficult to read, but I'd say these should be enough to bump it down to playable instead of verified.
The Deck mode (enabled by default) causes extreme ghosting due to FSR being set to a performance mode (you cannot change this). It looks atrocious and it'll make it impossible to see the ranged combat "reticle" along with other environmental details. You can disable the Deck mode with a command line, which allows you to set FSR to quality, but that'll cause performance issues.
It runs well enough if you're playing with the Deck mode enabled (default), but there are dips in framerate here and there.
All in all, it runs well enough all things considered, but it's hard to swallow when it looks this bad thanks to the heavy ghosting caused by FSR. I tried both the Deck mode, which was fairly playable, and the PC mode, which looked better with FSR set to quality but came with much more dips in performance. Also, the UI has plenty of elements, text and otherwise, that are quite difficult to read.

Even without a gaming focused distro and bellow minimum requirements, I had a great time beating this game.
VKD3D_SHADER_MODEL=6_6 gamemoderun %command%
But my hardware is bellow the minimum requirements.

Using mangohud with this game causes severe graphical degregation, in the form of lots of white dots appearing whenever things move. It makes it unplayable.
Not starting mangohud yields a perfectly playable experience.
My graphics card is at the very lower end of the minimum requirements for the game, I am assuming that is what causes the issue with mangohud.
When using mangohud as described elsewhere. Just startting game with no tinkering yields good graphics.
My experience is with the latest patched game at this point - i.e. 1.5 It is perfectly playable with no tinkering on my hardware.

VKD3D_CONFIG=dxr VKD3D_FEATURE_LEVEL=12_2 VKD3D_SHADER_MODEL=6_6 %command%
Now is working fine, the problem was on the directx12.

gamemoderun mangohud %command%
Weird repetitive vertical screen artifact no matter what I did with any settings

This game is not working since patch 1.5
I try it in steam deck and PC, but the game closes on launch.

When entering a new area slight stutters. Just wait a second or two and it's fine.

Playing online with my wife without issues

Cutscenes have sound effects dulled on the right side, voices only come in from the right side as well.
Running the game in a borderless window causes it to take up 100% CPU and cause thermal shutdown.
Like many titles, this game will not detect a DS5 controller unless it's plugged in or has Steam Input enabled (causing incorrect button prompts). This is a hardware issue with hid-playstation on certain kernels.
Crashing during a cutscene or the like will pretty much necessitate restarting your playthrough, since it can cause numerous bugs and instabilities.
Overheats and murders my fucking laptop every 20 minutes. I have good thermals, too.
Occasionally hangs up on alt-tabbing

DXVK_ASYNC=1 PROTON_NO_ESYNC=1 mangohud gamemoderun %command%
Skyrest Bridge can be extremely laggy, dropping from 150+ frames to 30 when loading the area via Vestige of Ethryg and running around the area. This also happens when re-entering the boss arena during the Pieta fight, which can last for 10+ seconds before stabilising. Other areas can also exhibit stutter and dropped frames but the game is otherwise perfectly playable on my setup.
All performance issues aside, the game plays perfectly with no other issues to report. According to discussions on the game, it is the game itself or rather most likely Unreal Engine 5. Hopefully developers will tidy the performance up but under most circumstances, at least for my hardware, it plays great and loved my time with it.
And unlike some others have mentioned, I've not experienced a single crash in my entire 50 hours of play, plus PVP seems to work great so I assume co-op play will as well.

MANGOHUD=1 VKD3D_CONFIG=dxr VKD3D_FEATURE_LEVEL=12_2 VKD3D_SHADER_MODEL=6_6 GAMEMODERUN=1 %command%
Needed these options: MANGOHUD=1 VKD3D_CONFIG=dxr VKD3D_FEATURE_LEVEL=12_2 VKD3D_SHADER_MODEL=6_6 GAMEMODERUN=1 %command%

Plays almost perfectly with the ocassional crash!
Can't open the steam overlay
Crashed once, made my whole computer crash
Works perfectly fine with the exception of the steam overlay not working. Before I had issues with my DS4 controller but the developers seem to have fixed the issue now, as well as a bug that would cause the frame rate to drop on rumble. Thanks devs!

Framerate is unstable causing significant microstuttering to extended drops during some areas.
PROTON_ENABLE_NVAPI=1 PROTON_HIDE_NVIDIA_GPU=0 VKD3D_CONFIG=dxr mangohud gamemoderun %command%
Some sounds only playing in left/right audio channel. E.G voices coming solely from right speaker. Cutscenes only.
FSR introduces significant artifacting.
Performance is pretty unstable, regular stuttering when autosave kicks in

MANGOHUD=1 gamemoderun %command%
Consistent frame rates are not possible. If you want to get high framerates FSR is required but a static like effect happens in many areas. its very distracting. Sub par performance all around. It has gotten some better with most recent patch

Multiplayer broken
Patch 1.1.362 yet again breaks multiplayer. These devs are a pain in the ass.

Its good. Performances seems worse than Windows but its still perfectly playable past the first launch.
PROTON_ENABLE_NVAPI=1 PROTON_HIDE_NVIDIA_GPU=0 VKD3D_CONFIG=dxr %command%
Bad framerate on first launch and character creator. Then, only the hub area has slow fps (still playable), rest of the game is perfectly fine.
Got one freeze, but it happens on Windows too.

My DualShock 4 controlled was not detected by the game regardless of what I tried as far as it came to Steam Input, the controller works fine on other games. I managed to work around it by pairing using bluetooth, and then running ds4dvr using the command python3 -m ds4drv --hidraw --emulate-xpad
which did the trick
My DualShock 4 was not detected, had to use ds4drv and emulate an xpad for the game to detect it
Slight frame drops when the rumble was activated on the controller
Plays great, similar performance as what I experienced on Windows with the exception of the frameloss on rumble, no deal breakers so far, except the controller issue that almost made me reinstall Windows

Unplayable framerate, hang when loading into gameplay
mangohud gamemoderun %command%
FPS is all over the place, barely running at a reasonable rate in the character creation screen and initial cutscenes. Game hangs when attempting to load into gameplay.

After the 1.1.310 patch on 9NOV2023 Multiplayer now full works as intended and smoother than on Windows.
Everything now works as intended and was able to fuly complete all game content with no issues and smoother gameplay than on Windows, and have verified 100% that multiplayer now works! Load it up and enjoy!

MANGOHUD=1 VKD3D_CONFIG=dxr VKD3D_FEATURE_LEVEL=12_2 VKD3D_SHADER_MODEL=6_6 GAMEMODERUN=1 %command%
If not launching directly from Steam, or launching a pirated version of the game, launch [gamefolder]/LOTF2/Binaries/Win64/LOTF2-Win64-Shipping.exe instead of [gamefolder]/LOTF2.exe
Multiplayer now working as of the latest patch. However, overlays such as mangohud and vkbasalt running will disable online functionality.

Game works out of the box with no issues. Since today the multiplayer is also working and I didn't have any issues with it either. :)

VK_ICD_FILENAMES=/usr/share/vulkan/icd.d/radeon_icd.i686.json:/usr/share/vulkan/icd.d/radeon_icd.x86_64.json %command%
Cannot login to play online on Linux
The game works with AMD GPU when using these launch options. But the login does not work anymore.

MANGOHUD=1 VKD3D_CONFIG=dxr VKD3D_FEATURE_LEVEL=12_2 VKD3D_SHADER_MODEL=6_6 gamemoderun %command%
DX12 error although that was resolved by using VKD3D_SHADER_MODEL=6_6

mangohud %command%
After Patch v1.1.243, the game stopped loading entirely and produced a -dx12 error.
Other launch options tied with no success: mangohud VK_ICD_FILENAMES=/usr/share/vulkan/icd.d/radeon_icd.x86_64.json %command%

Online functionality stopped after I played on a Windows PC for a bit and returned to the Steam Deck