On: Fuzix OS: Unix for the Z80 and 680x

[lproven]

The Spectrum Next? ;-)

If you can't get one, and who can -- then the N-GO is a good alternative.

https://manuferhi.com/c/n-go

There are other clones out there, e.g. Sizif 512: https://github.com/UzixLS/zx-sizif-512

But for modern kit, readily available, probably the Agon Light:

https://www.thebyteattic.com/p/agon.html

E.g.

https://www.olimex.com/Products/Retro-Computers/AgonLight2/o...