Sending files to another would be easy if only the services that allow doing this - over WebRTC - didn’t sell out to sketchy advertisers constantly. I have to look up which service is still good to use every time.

That's because they're actually not "sending files to another". A hairpin service has to be provided for double NATed scenarios and a rendezvous service has to be provided for all cases. There's no magic about WebRTC that makes it actually p2p.