Had this error, which is related to SELinux: ./stellaris: error while loading shared libraries: libpops_api.so: cannot enable executable stack as shared object requires: Permission denied

Found the solution on https://forum.paradoxplaza.com/forum/threads/stellaris-does-not-launch-on-selinux-enabled-systems.1562601/

Basically, run sudo find / -name libpops_api.so, find the one with Steam and Stellaris, install execstack, run execstack -c (the path you found). Worked immediately.