AV amps / upmixing from 5.1 (DVDs etc) to 7.1+

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TL;DR: Are AV receivers / AV amps that upmix from 5.1 --> 7.1 still a 'thing'?

I have googled
av amplifier with 5.1 upmix
av amplifier with dolby IIx
etc.

Most of the stuff that comes up seems out-of-date, and I can't find any currently available AV amps that advertise Dolby Pro Logic IIx.

So it looks like PL IIx is out-of-date tech - and sure enough, there seems to be a (newer?) equivalent, DTS Virtual:X. However I've read that DTS V:X won't work with Dolby 5.1 sources!! Which is surely exactly what I have if I play an old-fashioned DVD with basic 5.1 surround?

Please can someone bring me up-to-date on this? None of the AV amps I've looked at seem to advertise "upmixing" as a feature, which leaves me wondering - is that because they all feature upmixing now, so they don't bother saying it? Or is it because 5.1>>7.1 upmixing has gone out of fashion?

All I want is a basic AV amp to connect 7.1 speakers, and watch DVDs/BluRays and play PC games in surround. (I don't need to upmix 2-channel audio. I like regular stereo music as the music producers intended.)

I heard from multiple sources that Dolby IIx was genuinely good! (To complicate matters, I've read about Dolby banning manufacturers from offering upmixing capabilities, but then later lifting the ban...)

Thanks in advance 🙏