Aren't most retrocomputing USB devices running open source firmware? Adding a descriptor "WebUSB supported" is a few commits and a firmware update away.
replythat's not going to work for use cases like the https://webmd.pro where you're interfacing with hardware from other manufacturers
replyDefinitely not most MiniDisc players. I doubt mine even has updatable firmware!
replyThis probably applies to many older (or even newer) USB devices as well.