Really worthwhile goal no matter what anybody says :)

Did a little testing myself.

Tried it on some bare metal, looks pretty good.

There were two phases, wouldn't fit in a single comment.

Wrote RetrOS-32.img to a blank SSD and it boots in CSM/Legacy mode.

That's a nice milestone right there :)

This was on a tiny Lenovo desktop about as old as an x240. These are low-power, run on the same Thinkpad A/C adapter, so there are some similarities to a laptop.

But the cursor wasn't very responsive and wouldn't come down below the very top rows either so could not sign in. Using mainstream wired mouse & kybd. (The PC has 8GB memory, in the login box it showed the nominal 15mb, but extended memory was a negative number, about 8GB itself.)

Then I remembered things like the x240 often have a touchpad that is recognized as a PS/2 mouse, not USB. Moved the SSD to an old tower that has a PS/2 mouse and kybd and then could sign on. Cursor was still quite a bit sluggish, but it worked. This one has 12GB memory and the reported extended was about 464mb so it looked realistic in the login box.

It boots! It works nominally! It's some kind of Golden IMG already, so congratulations!

Back at the Lenovo I do boot to DOS from time to time, and I enable Legacy USB in the BIOS so I can use the USB mouse for DOS which had no concept of USB. After booting DOS, if I want to use the mouse I still have to load DOS mouse drivers, just like the 1980's but this firmware setting fools the old pre-USB DOS mouse driver so it will handle the USB mouse & kybd that people are using now. This setting has been there for ages since the PS/2 sockets on PC's started becoming scarce. Checked the BIOS, and Legacy USB was enabled the whole time.

However, on this Lenovo there was an additional setting, for "USB Virtual KBC Support". I don't know if I ever saw this along with Legacy USB settings in one BIOS, up to now would have assumed they were both the same thing but using different terminology. This setting was not only disabled by default, the text says this one auto-disables once an XHCI driver has been loaded. Then definitely found it to auto-disable after booting Windows.

Enabled Virtual KBC, booted to RetrOS and the USB mouse could log in. More sluggish cursor than on the PS/2 machine though.

Plus there were some untyped characters that would sometimes appear when logging in, or admin would duplicate itself so username said adminadmin after you typed in the password below.

Still has a huge negative number in the login box for extended mem, that was not a show-stopper, mem appears normal when looking at the system stats once logged in.

I would now imagine this Virtual KBC setting emulates how mouse & kybd are presented to a VM?

Interesting finding that DOS does not require this setting for a USB mouse to work on bare metal, but RetrOS does.

Have not put it through its paces thoroughly, focusing on the bare metal aspect.