you do know microsoft OS 2.0 descriptors are a thing, right? or that you can force the unknown device to use WinUSB
but really most devices you want to interface to via webusb are CDC and DFU so.. problem solved?
I'm unfamiliar with the Windows platform but that sounds like something that still requires executing code locally.
.. or HID ( https://usevia.app/ , for programmable keyboards)
I'm unfamiliar with the Windows platform but that sounds like something that still requires executing code locally.