Years ago I went down the route of trying to get USB over browser and it was not happening. Best I came up with was that if we did some real tricky stuff with making the device a “printer” and using some usb/printer emulation stuff. Abandoned it.
We tried a similar method of playing audio from the browser when its actually serial data. I think there are a few arduino platforms doing this now and it works on PCs and phones.
Yes, unfortunately it is Chrome only. The good news is that our device didnt really have to change at all to support Chrome. Most hardware devices' bootloaders support DFU (Device Firmware Update) so all we had to do was support DFU on our website.
I assume like webBLE, that webUSB is Chrome only?