Worked fine. I did:
Install Lutris
From there: Install EpicGamesStore
From there: Create "epic" account and login
From there: Install GTA 5
From there: Download 97G (wat!)
From there: Go to sleep and wait for shitty North American internet
From there: Launch RockStar Social Games Launcher (it might have crashed once here, but on relaunch it was fine)
From there: Register for new account, fight with captcha
From there: Login to new account, fight with captcha
From there: Finally launch GTA5 (crashes and launch in safemode I think here)
From there: GTA5 works...
From there: Start game, see ads about rockstar games DLC and gambling nonsense
Sadly my hardware isn't fast enough to play this on any appreciable quality or framerate, so it was all for nothing :(
Also pretty impressed how user-hostile rockstar games is and how anti-linux rockstar and epic games are. And the captcha nonsense is absurd.
But that's how you make it all work if you've got the hardware for it.
SOCIAL SHARE CARD GENERATOR