practically though what is the difference between having the endpoint in a shaft by the elevator or in your apartment or even down the street? in all scenarios i'd put my own router behind the ISP equipment and run my local network however i want.

the only issue is with getting a public ip address for inbound connections.

here we are not getting public ip addresses anyways, so the point is moot for me. but if you do get one, then all they need to do is configure their router to forward the public ip to yours.

in my case the ISP even installed two routers. one was theirs that i had no access to and one was "ours" that i was able to configure as i liked or replace with my own. both routers had their own wifi, but i don't use the one from the ISP endpoint router