I set up a small Ubiquiti setup with Pi-hole, then moved into a home serviced by AT&T Fiber, which comes with an all in one fiber modem and WiFi hub. I started using it before I could unpack, then did a little research on how I could disable WiFi, DHCP, and/or DNS in order to use my own equipment. The WiFi isn't great in all parts of the house so I planned on setting up APs at strategic points. But of course laziness, fear of stuff breaking and my family getting mad at me, and WiFi entrenchment has stopped me from using any of the equipment I bought. I would one day love to switch back over, but I just don't see it happening soon.
There was a guy on dslreports selling certificates for $10 each, and you could just load it up into one of the cheap sfp modules off of aliexpress. Plug it straight into the router of your choice. No reason to use their junk. I've done the same with a different provider.
I use ATT Fiber and using the pass-through mode has worked pretty well for me. The main problem is their box is still a piece of shit that they introduce bugs/regressions into sometimes. But that'll affect their own service as well, regardless of whether you use your own device w/ passthrough. So you might as well hook your stuff up.