If Intel HD Audio isn't backwards compatible with AC97, well that's disappointing I guess. Though I'll admit I have no idea how sound works (i.e. I don't remember how any of that was setup in an old 486 my mom had xD),
I just assumed it was possible because my cousin had sound in the DOS version of NO$GBA, in a Compaq Deskpro, ran on a Pentium II with a dual-boot to a perfectly functional Windows XP. I don't remember any more details, other than both his PC and this laptop use similar BIOS; both come from the same codebase, menus have the same interface, I just got a slightly more updated version.
Yes, selecting an option adds settings into autoexec.bat, i.e. a %BLASTER% variable that some programs (such as Pinball Fantasies' SETSOUND) use to pre-select some options, not sure if any program outright goes to the letter without more option. Just thought a typical Sound Blaster setup needed an additional SYS file or something like that, I think I'm wrong here.
By the way, this MS-DOS 7.1's setup might be unofficial and it's not that much known I think (made by Chinese DOS Union), but IMO it has not only proven to be highly useful (for one it's already more featured than MS-DOS 6.22 + Supp disk), it also features some of the most inspiring batch files I ever read in my life, yet criminally underrated. In fact (and I hope not to look racist), compared to the coding quality from many chinese famicom games, this setup is actually quite stable, and quite polished, like a polar opposite. And I think that's quite interesting.