If this comparison helps: before deprecation, the last practical use for AppleTalk was file sharing, e.g. legacy Time Machine. Apple dropped it, and encourages SMB and WebDAV.

Thank you, highly appreciated! Now everything makes sense.

https://en.wikipedia.org/wiki/AppleTalk was very thorough on the protocol's history, but I was really puzzled by the purpose and why somebody would re-implement a discontinued protocol.

More information on that here:

https://en.wikipedia.org/wiki/Apple_Filing_Protocol

AppleTalk is a protocol that was used on classic/vintage Macs (think: early/late 1980s, 1990s) to create local networks. The wikipedia page [0] has a good historical overview, including the parallel rise of ethernet / tcp/ip (which won).

[0] https://en.wikipedia.org/wiki/AppleTalk

How does TailTalk relate to this? Does it re-implement it?

Using TailTalk on my modern Mac, I can expose a file share accessible to my Macintosh Plus, which has a simulated SCSI Ethernet adapter bridged to a Pi Pico 2W's wireless connection via a BlueSCSI.

Yep, looks like it - it's a from-scratch reimplementation that you can use in your own software to talk to devices on AppleTalk networks.

If you’re reading “Hacker” “News” either this sequence of English words should make sense to you or you should be competent enough to use a search engine and/or Wikipedia to easily learn what they mean.