Moved from Fi to AT&T... OS updates?

Moved from Fi to AT&T... OS updates?

Hi, all-

I bought my Nexus 5x from Google, and tried Fi for 2 months before deciding its coverage wasn't working for me. I popped in an AT&T SIM and am now up and running smoothly with them.

My only question is... How do I now get updates? Since the Nexus 5x is not a phone AT&T offers, I assume they don't provide OTA updates of any kind for it, am I right? I loved getting the monthly security updates when I was on Fi, and did manage to upgrade to Nougat before leaving... but I'm concerned about how to stay current going forward.

Any idea? Thanks in advance for any light you can shed!

-Mark