Audio input is quite recent. For sure we need more info about it … jeje! But we have some entries:
Regarding the latency, zynthian “hardware” latency is quite low when using I2S, although i can’t give you a number. Anyway, is low enough so you don’t need to worry about it. Normally, in zynthian, “software” latency is bigger than hardware one, and software latency can be adjusted via jackd parameters. By default it’s configured to 5.8 ms but it can be changed easily …
Regards,