Getting back to Doom95, I think there's some kind of bug in the code... 320x200 fullscreen 256 colour with DirectDraw 1.0 works on Windows 10, at least, with my code.
So Doom95 may be making some wrong assumptions in the initialization code for DirectDraw, perhaps requesting something that modern videocards do not support.
I also find it somewhat strange that it draws to a window even though the pixel format is obviously wrong. I tried some compatibility settings, and then my GeForce started to give the same error message as my Intel one: that Doom95 can't access the videocard (or whatever the exact message was).
I'll have to set up some DirectDraw 1.0 windowed code for 256 colours to see if that can work in Windows 10.
Perhaps I get some useful error codes from that, and just maybe I may be able to compare that to what Doom95 is trying to do.
TL;DR: I suspect the problem is in the Doom95 code, not in Windows 10.
"Working code is not bugfree code"