Ok, so I followed the guide from CommandMC (https://github.com/CommandMC/EpicLinux/wiki/GTA-V) and everything worked fine, except for the R* launcher. At first the login window was broken, I couldn't enter anything into the textboxes(screenshot). Then after trying a few more times it somehow skipped the login, but SocialClubHelper.exe kept crashing, thus the game wouldn't let me play.