https://community.signalusers.org/t/how-to-get-signal-apks-o...
Running a server environment is probably time consuming ane expensive, but that's kind of why the people running the servers get to set the rules.
Maybe running your own network will help explain why they do things the way you don't like. Maybe running your own network will help explain how running things the way you like can actually work.
You also can't communicate with WhatsApp users directly either.
If your fork of Signal in better, then you should have no difficulty it convincing people to switch to it. Just because the software is open source, you're not entitled to connect to and use someone else's service in any way you like.
Yes, convincing the Signal team to address their particular issues would be a much easier path for them, but a) again, they are not entitled to anything, and b) attempting to convince by acting childishly and ignoring the Signal team's wishes is not a great way to convince anyone of anything.