Lenovo Legion 5 Pro 16ACH6H (Ryzen 7 5800, RTX 3070). Fresh install of Nobara 39 Official, AMD & Nvidia GK drivers, & Steam installed - the game would get to main menu OK, but when loading or starting a new game it would hang on loading screen at circa 75%. Waited for 5 minutes but nothing happened. Fiddled with various Proton versions and command lines found online but still no go. Eventually found "__NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia" on the Nobara website and it then worked perfectly. Still takes longer to load than on Windows, but runs perfectly.