AppleCare for Enterprise on former company device

Welcome!

As AC is linked to serial numbers, I would start with this page to see if Apple still shows coverage for the device:

Check Your Service and Support Coverage - Apple Support

...but since they no longer own it, it reverts to "basic tier" AppleCare, meaning it's still covered just not for accidental damage.

I've not heard of that—especially the "tiered" part—but then none of us here work for Apple and there is little to no support for managed devices in these consumer forums. I think you need to chat up Apple, as we can't provide you with a definitive or binding answer.

Any update? I'm in the same position