Cool project! I'm thinking of putting Coreboot onto my T440 when I'm done with Windows on it.
That's not just yet though. I think you've found the best OSs already, but I'm suggesting
MikeOS even though MichalOS is closely related. Some people do like to run both. I found a quick summary of the differences which I can't quite remember. Something like MichalOS has more toys but MikeOS more coding tools... maybe. Recent changes in MikeOS include a BASIC compiler and extra documentation for its Forth.
I like OSs which boot to an interpreter for a full programming language, (not just a shell,) but they're a bit hard to come by. Colorforth is about the only one I kind-of know where to find, but its got that krazy keyboard input. Oh, and it's supposed to save back to the floppy disk it booted from, and you really need to keep rotating backups. Never mind that, then. Several more traditional DOS Forths could be native but there's little point porting them, otherwise I'd have one to offer.
I almost thought I had a Lisp OS to suggest in the form of
Mezzano, but its iso image unpacks to 500MB! It's only 85MB compressed, hence my hopes. I have no idea if it could be rebuilt to fit on a floppy. Anyway, to quote its README, "But to set expectations: making Mezzano run on any given piece of hardware or emulator is still typically a project that requires the user to dig into the code." I wouldn't be surprised if the majority of hobby OSs are in this state. Linux was short on drivers when I started using it, and that was when it was already powering 70% of the WWW!
I'm sure there are one or two bootable BASIC interpreters, but it's hard to search for them amongst the various OSs written in FreeBASIC. FreeBASIC is not an interpreter, and takes BASIC in a direction I don't like. BootBASIC is just too minimal to bother including; at 512 bytes, quite a lot had to be left out. It's more fun looking at and modifying its source than actually using it. I was extending it, but then I had one of my attacks of "Why am I doing this?" lol
And there's PonyDOS! It's both hilarious and an impressive feat of minimalism, but it's another one-disk wonder and it can't really do anything useful. I don't think any of the programs can even save to disk.
I'm surprised by how limiting the restrictions are, that it must fit on a floppy, boot from BIOS, and do something interesting. I would have suggested Kuroko as a bootable Python-like language, but it boots from UEFI. You would have had much better results 20 years ago, but coreboot didn't exist then.
That said, there are a lot of hobby OSs I can't recommend because I never bother trying OSs which don't distribute binary images.
Sorry for the late reply, there was an awful backlog of posts waiting to be approved. The situation should be much better from now on, as we have several new moderators who are active forum members. But speaking of activity, many OS devs only come here intermittently, perhaps because OS development is such a long-term project that they take long breaks. This may explain why you haven't had any other replies.
