This is why the market needs some regulation. Here in The Netherlands, ISPs are required to offer free (as in freedom) modem/router choice. Not only can you replace the router, you can even use your own XGS-PON/AON/etc. SFP(+) module.
For a while I had fiber running through an XGS-PON SFP module in my own Fritz!Box. Now I use the provider's ONT (which is just a fiber <-> ethernet media converter) hooked up to a Unifi Cloud Gateway Max.
Plenty of folks here that have their UDM or OpnSense box hooked up directly to fiber with a Zaram XGS-PON module.
Also, I am sorry you have to deal with caps. Data has been unlimited here ever since we switched from 56k6 to ADSL. (I also have unlimited 5G for 25 Euro per month.)
For a while I had fiber running through an XGS-PON SFP module in my own Fritz!Box. Now I use the provider's ONT (which is just a fiber <-> ethernet media converter) hooked up to a Unifi Cloud Gateway Max.
Plenty of folks here that have their UDM or OpnSense box hooked up directly to fiber with a Zaram XGS-PON module.
Also, I am sorry you have to deal with caps. Data has been unlimited here ever since we switched from 56k6 to ADSL. (I also have unlimited 5G for 25 Euro per month.)