Source code: https://github.com/mhsys/mh
"MH is free software" and there's a link to GNU, but I don't see an actual license anywhere.
"it is possible to use NetBSD drivers, filesystem and other code in userspace to driver real hardware, it has a complete libc in userspace, Newlib, and has a really useful native runtime system, libmrg" - that is promising, even though there are notes about this still being early / not useful, etc.
> The MH development repository has moved from https://github.com/glguida/mh to https://github.com/mhsys.
> Now that we have multiple external projects, like rumprun-mrg, and a strong interest in adding more ports for the mh userspace, it make sense to have a place to have all MH related code.
Thank you for your interest btw; this was completely unexpected and a rather pleasant surprise!
Development is currently stalled mostly for personal reasons, but I am more than available to help and answer questions to anyone interested in it.