I'd quite like to know how it runs on an Xbox, controls wise.
It doesnt. There is currently no XBox version because Microsoft have a version parity policy which means if the offer a feature on the XBox X they need to offer it on the XBox S as well, and they cant get split screen to work well enough on the series S.
Apparently Microsoft have decided that in this case they dont mind and Larian can ignore the policy, but they only decided that
after BG3 had already released on the PC to huge aclaim, so its still set the XBox version back many months. Larian appraoched them back in Jan about releasing the series S without split screen and microsoft said no, the two versions needed to be identical. Larian refused to just drop features from the series X version, to make them identical so the two companies ended up at an impass. Larian had a team trying to optimise the XBox series S version to the point where split screen worked, and planned to increase the size of that team after the PC and PS5 release window. BG3 then got a 97% critic score on Metacritic and for 3 weeks was the best reviewed PC game ever and Microsoft changed their colours, but it was too late. Effectively a single Microsoft policy made this a PS5 exclusive.
However the control scheme on the PS5 is surprisingly good - in fact for general exploring and conversation I prefer it. For inventory management not so much. Generally though its comparible - better in some regards, inferior in others. Also it runs graet using an XBox controller on a PC.