Metal boots into a persistent native MicroPython REPL pymergetic on GitHub has created Metal, an experimental UEFI/BIOS freestanding async runtime. It is not a conventional OS and it is very far from production-ready, but it now boots directly into a persistent interactive MicroPython REPL.
The repository is at https://github.com/pymergetic/metal. See more in the MicroPython forums.
CHUCKYSCARNAGE 