I got it to work! I don't have time to write it up fully, but if you can get an NFC Ring added as a trusted device under Smart Lock, the steps to use it seem to be:

1. Wake up the phone - if Smart Lock is configured, there should be a closed, filled-in lock icon at the bottom of Android's lock screen with a pulsing circle around it.
2. Scan the ring - if it recognizes it, the lock will open and change to an outlined image instead of filled, and a soft pop or click will play.
3. Swipe away the lock screen, and the phone should be unlocked. The NFC Ring Unlock screen didn't appear, and I have access to my phone at that point.

I have my phone configured with a PIN, but can skip it and the still-active NFC Ring Unlock by scanning my ring. I can answer questions tomorrow, I'll try to check back.

I got it to work! I don't have time to write it up fully, but if you can get an NFC Ring added as a trusted device under Smart Lock, the steps to use it seem to be:

1. Wake up the phone - if Smart Lock is configured, there should be a closed, filled-in lock icon at the bottom of Android's lock screen with a pulsing circle around it.
2. Scan the ring - if it recognizes it, the lock will open and change to an outlined image instead of filled, and a soft pop or click will play.
3. Swipe away the lock screen, and the phone should be unlocked. The NFC Ring Unlock screen didn't appear, and I have access to my phone at that point.

I have my phone configured with a PIN, but can skip it and the still-active NFC Ring Unlock by scanning my ring. I can answer questions tomorrow, I'll try to check back.

For me, the process was:

• set a pin
• go to trust agents
• enable smart lock
• disable NFC Unlock (as this locked out the Smart Lock options on my phone)
• add my ring as a trusted NFC device

Something like that, at least. My ring is pretty finicky at unlocking the phone in this way - I have to make sure the ring is scanned before I swipe, but it either doesn't play the NFC read sound, or only reads 1 out of 10 times successfully. In any case, if the ring is read when I swipe, it bypasses the number lock.