There's a kernel module for handling the networking connection and exposing it as an alsa device: https://bitbucket.org/MergingTechnologies/ravenna-alsa-lkm/s..., and some FOSS stuff for managing the discovery/control layer. It's not as simple as plugging in a USB device and selecting your i/o, though.

Ooooh something I know quite a lot about:

So for AES67 receive, in principle no as PTP stack exists for RPI yet. You could cheat like the majority of manufacturers do and just play the audio as it arrives instead of using the timestamps. You'd also need a way of drifting the audio out clock to match the frequency of the PTP clock. If you didn't care about bitexact audio, you can resample, though ALSAs clock measurement kind of sucks.