That's a great idea! The protocol can be implemented entirely separate from this first TypeScript client application. If anyone out there has gnuradio experience, I'd love to chat with them / offer support. I'd imagine the more folks use it the more we'd learn what modifications to v1 of the protocol would be useful.

This looks like it implements the packet processing only, and suggests using Direwolf as a software AX.25 modem. Direwolf can decode audio piped from rtl_fm or gqrx, so using a SDR is likely already possible for receive; not sure about transmit.