[BrandoElFollito]

I live in France so obviously I won't help you directly. I guess however that there is a whole community of people in the US who documented "how to replace the box from provider X by the device Y".

Depending on the details, it can go from plugging your fibre directly into a small factor PC, to not being able to do it because even bridging is not available on the box and everything is proprietary.

I for instance replaced the shitty Livebox 3 from my French provider Orange with a PC running Debian. Before that it was a Ubiquity Edge Router 4.

Orange make it difficult to change the device, but not impossible. I would love them to just provide my IP though a standard authenticated DHCP request.