If you want to use special router functions that cannot be realised on a Swisscom Internet box, there is nothing to stop you from cascading an additional purely internal network with your own broadband router behind it.
As a result, your own network will be mostly provider-neutral, because your own router doesn’t care what kind of “provider device” with whatever technology it uses to access the Internet.
Hobby-Nerd ohne wirtschaftliche Abhängigkeiten zur Swisscom