Just installed my G6 entry pro, and I didn't do too much research upfront. I understand that I need a door hub (looking at the Mini) to get the FaceID / Access features enabled.
I have a Yale Doorman V2 integrated to HA through my alarm provider (Verisure), which I can lock / unlock through HA. My idea is that it would be nice to use the FaceID unlock feature (triggering an automation in HA to unlock the door) for my kids.
Is it possible to get unlock triggers to HA through the Unifi Access integration, or is it a hard requirement to have a door hub hardwired to the lock? Ubiquiti support says I need to wire, but I got the feeling it was a hard read on the requirements page they were quoting.
It's possible.
In Unifi Protect, you need to set up an alarm for recognized faces that triggers a webhook. That webhook should then trigger an automation in Home Assistant that unlocks the door.
It works for me—I'm using a G6 Entry and a Yale Entrus.
All I needed to know, ordering a hub mini now! Thanks 
Did you just get an answer that it's possible without Door Hub wired, then told us you're ordering the Door Hub? Am I missing something?
Yes, that is correct. The door hub enables me to open my non-unifi door lock (with no wires) through Home Assistant. I have it set up and working.
I have no hub, but a Yale Entrus lock, that opens using the Yale integration.
unifi protect, triggers an alarm, that using a webhook starts an HA automation, that unlocks my door