Oh great, another API that dodgy sites will try to trick users into giving access to (see also every "do you want notifications from this site?" popup)
First thing I do with my Chrome is opening Settings/Site Settigs, Additional Permissions and blocking almost everything in this list. There's surprising number of APIs that I'll never need (MIDI devices? I have no idea what MIDI device is and I definitely don't own one. Payment handlers? I'm using cash, thanks. Augmented reality? I'm fine with ordinary one, thanks.).
MIDI devices mostly refer to musical controllers. With it, you can plug a controller and play piano on https://pianu.com, for example. I use it sometimes.