This is not helpful (I realize that), but from experience this is one of these, ‘your mileage may vary’.
It may well depend upon a certain level of wine, etc.
I don’t recall if I ever tried DOS2 under Linux. I seem to recall BG3 (also Larian developed) being trouble and just not worth while to try.
I was playing the game in the recent weeks on and off with no problems (30 hours, Intel Arc). Now it crashes on the loading screen here too. Switching from Proton Experimental to Proton 8 works.
Proton 8.0 is the solution! Thanks @Schlaefer, I was getting desperate. It runs like butter on ultra settings with the old RX 580 and the much older i5 2500K (but without overclocking).