I've been a bit lazy and haven't finished my migration off of google and MS services... I have mixed feelings about my testing of nextcloud and the like. I've got a pretty solid mail solution (mailu) going, but even with that I don't have it on a domain/address I rely on. I'm mostly using a wildcard forward on one of my domains so I can assign a different address to most online and offline accounts as reference.
All three domestic providers do the "we are working in your area" which where it comes to my building "nah" is said and the promises of fast broadband suddenly disappear.
I've been living here 8 years now. Same thing said each year.
I have even asked if I provided the equipment run a Line-of-Sight links from the hotel to my apartment. Perfect range and advantage point but nothing other than some PR fluff of "it may harm the public".
BT sells internet service, transit, and buried cables. You want to do what the hotel did and buy a buried cable from them, and then buy transit. You’ll need to do like the guy in the video did and rent some space in their colocation facility to put your gateway in. Plug your buried cable into your gateway, plug your gateway into their router, turn on BGP, etc.
They also offer an intermediate service called a “leased line” which is a buried cable plus transit plus they handle all of the networking for you as if you were a consumer. The hotel chain might have gone that route as well, although there are clear advantages to having your own AS. You can figure out exactly what they did if you connect to their guest WiFi and run `traceroute -A`…
Of course your apartment manager (or the owner) might not agree to let you bury your cable on their property. They might even have an exclusivity agreement with the cable company. This could even be the reason why no other ISP is available in your apartment building.