looks like no.

The official release notes:
https://baldursgate3.game/news/patch-4-now-live_96

I used "Ctrl + F" to look for keywords such as "split", "local" or "fullscreen".

So I just submitted another ticket for merged screen:
https://larian.com/support/baldur-s-gate-3

Anyone is welcome to submit one so the devs will know the demand is there. Thanks!