yeah I played bg3 with controller split screen with my wife the entire playthrough. Normally, I would've strongly preferred KB+M for such a game. We definitely got used to it after several hours.

I'm not sure if I can recall any tips other than just keep at it and it'll eventually become muscle memory. I don't think it's as good as KB+M but it wasn't something that was bugging me once we got significantly into the game. YMMV.