This can be closed imho.
Here's 6.8 staging with current vkd3d-proton head:

The game will crash with it (at least in borderless fs), but the option is there. The bug as been marked as invalid on winehq.
Also a duplicate of https://github.com/HansKristian-Work/vkd3d-proton/issues/434
Yeah sorry - forgot to close it last night when I was reviewing my bugs.
Just cross posting this to keep you in the loop on this "bug".
https://bugs.winehq.org/show_bug.cgi?id=51062#c11