So, progress on the Hyper-V front.
I feared for a minute or two that Hyper-V wasn’t really even as good as VirtualBox (and.. well.. jury might still be out). I have got sound working, and full screen resolution working.
And I don’t even have to use Ubuntu.
From a new .vhdx on my fastest spare SSD, I installed Debian amd64 net install. The ethernet was not autodetected, but Hyper-V ethernet device such-and-such was in the list, so smooth sailing.
I had to edit /etc/defaults/grub or something, to add hyperv_fb=1600x1200 or something, but I found that would not work past 1600x1200 or 1920x1080. Specifically, 2560x1440 did not work. This seems to be a limitation of the Hyper-V framebuffer driver. So you’ll need to “graduate” to xrdp to get higher resolutions.
So install xrdp, and then use Windows 10 Remote Desktop Connection to remote-in, by the local IP address. Firewall seemed to be off by default or something. Full screen worked.
Except audio did not work. I had to compile pulseaudio (there’s a guide online) and copy the .so files so that xrdp sinks all audio into it, through to Windows.
It all seems to work with Debian, even better than Ubuntu, if anything.