That too is possible (serial ports though, not ADB). There are existing LocalTalk-to-Ethernet bridge products from long ago that are getting harder and harder to find. I was actually working on a new one for a while but ran out of the time/motivation to finish it up. https://mac68k.info/forums/thread.jspa?threadID=275&start=0&...
The kernel module implements the stuff described in the sections on EtherTalk and AppleTalk phase II on this [1] wiki page.
[1] https://en.wikipedia.org/wiki/AppleTalk