My understanding is the coleco vision bios is easily reverse engineered and replicated without violating copyright. Not sure about msx or sms, but based on some of the homebrew cartridges here copyright is not an issue.
... on another note .... given the CV, MSX and SMS use a BIOS is the user supposed to bring his own?
SW copyrights last so long that I doubt anyone can release anything with a BIOS in it in my lifetime without finding a way to get a license for the BIOS in question.
For MSX there's C-BIOS that may do in most (but not all) cases due to its BSD-clause, I am not aware of anything like that for CV and/or SMS.
Granted very many games may work without any BIOS at all, still.
Did I miss anything?
The sg1000 on the other hand is BIOS-less so no issues about it (as any HW patent have long expired), it can work right out of the box.
[I believe the BIOS-less nature of NES and SNES is what allowed Analogue to easily and legally ship the Nt Mini and Super Nt, and could allow a MegaDrive based release, obviously non TMSS but that is fine , that also matches all the FamiClone, NES/SNES/MD all in one clones we've seen in the last decade or so, funny as no-one attempted yet a PCE/TG16]