Modem Bypass 1551nm Module??

I've done a fair bit of research but I can't get my one question answered..am I on GPON, XGS-PON or something weird/different? Everything I've read makes it obvious that I'm on GPON, like references to GPON on the modem, the plan I bought etc etc.

Long story short, I just got my FS ONU in the mail today(exact one linked below), and I got the config data moved over onto it, got it in my UDM-Pro...and nothing. I went to the web page of the ONU and it showed -inf on RX power...which is an issue before any authentication via ATT comes into play..the only 2 things I can come to is either that module is just broken..which I really doubt, or I'm not on a GPON network.

My SFP module on the modem has that yellow handle and says its ALT SFP at 1551nm, which is far higher than GPON and XGS-PON..Though I've read that this could mean it is 'hybrid'(?) G/XGS-PON?? I can't find any definitive answer for what the 1551nm spec actually means, ChatGPT said it was "the max capability" for the module and doesn't mean what its operating at. And for the 'ALT SFP' it has nothing to do with the optics and is just the interfacing of the 'SFP' itself, which seems its not even actually SFP.

Anyways, idk, I'm stuck, lost, and everything inbetween..can someone provide some insight as to what I check/try next?

ONU I bought- https://www.fs.com/products/351565.html?attribute=124228&id=4833702