SM-N960U Software Update Issue

Hello,

I have an SM-N960U which I was using previously under AT&T in Massachusetts.

Due to the need to move to Europe, I unlocked the phone to be able using Europian Mobile Operators.

My Note is running on Android Version 8.1.0 and the last security patch is from 1st of November 2018.

I am willing to upgrade to Android Pie but from some post on the forum, I read that I must be on the US using AT&T service to get the updates.

Is there any way I can get updates from Europe or download the patches and updates from AT&T and install manually from my PC?

Thanks in advance,

Regards