omg, there's Net-MD software that uses WebUSB https://stefano.brilli.me/webminidisc/
(needs the WinUSB driver on Windows and device access on Linux)
the fact that is has 0 seconds left makes it look like it's definitely a commercial release, but it seems to be on a normal recordable minidisc?
yeah, it seems to have a magnetic layer and it has a write-protect notch? I wonder if it's actually writable