The most important difference is that kolibrios is a team effort, and open source.

Menuetos abandoned its 32bit version (the one that was open) to focus on 64bit, which is not, and even has a clause in the license that prohibits disassembly.

What is the commercial value of an artisinal OS like this?

Likely low powered computing scenarios. Think set-top boxes, kiosks, cash registers, etc. Anywhere you want to use very cheap hardware basically.

Cheaper then Raspberry Pi? With $15 for Zero variant? How much cheaper then that you can do really?

I'd say RPI it's the best in that regard. Also fully fledged Linux there, not some pet project OS.

Very cheap _x86_ hardware, to be specific.

I'm not sure if it's actually more expensive to find VIA et al based systems for cheaper than NUCs?

I don't know if VIA still does any of that.

But there's Vortex86.

It looks like the 64 bit version of MenuetOS is free for educational use, but costs money to use commercially while KolibriOS is GPL.

>educational use

Not much educational use to get from a system that is closed source and has a clause forbidding disassembly in the license.

*Disclaimer - I have never used MenuetOS

Regardless of being closed source, I'm going to guess that it would still be highly educational to learn Assembly programming on a system that makes it a first class citizen where you just boot into the OS that already is entirely built around ASM. For really simple stuff, a simple microcontroller might be better, but I'm sure some folks are more interested in building desktop apps.

You can do this using QEMU while using BIOS functions

That implies that the only educational use you can get from a software is trough reading its code.

Educational use most often means you learn how to use a software, not how it's made.

Autodesk gives free educational licenses for its software and I saw no one saying it's of no use.