Anyone made a USB driver for Mac OS 9?

I have a "Wallstreet" G3 Powerbook with a broken audio circuit (I can hear very faint, muffled audio when plugging in external speakers, so I guess there is a blown cap or IC in the amplifier).

I have tried plugging in a (modern) cheap USB audio dongle (the Wallstreet was the first powerbook with USB ports). It shows up as a USB device in the OS 9 system profiler but it won't make any sound. So I was thinking I would try and write my own driver extension for OS 9. I mostly only care about audio output.

Are there any old school classic/PPC Mac developers who have attempted such a thing? What am I getting myself into?

Are there any examples out there of open source OS 9 USB drivers (of any kind)?