This is kind of useless fear-mongering suited to no one's threat model.

Are messages truly E2EE and they don't share meta data? Yes? Then you're fine. It needs a phone number for registration? OK, well buy a burner SIM card (you of course have several, right?) to register it if you're that worried. Because if you're already at a level where you're THAT concerned about your phone number pinging for using a widely popular messaging app, then you have lost the game by even having a phone or sending messages to other humans who are the weakest link in the security chain anyway.

Considering that the Feds tried to make some government-compliant front end for Signal for idiot Hegseth to use to talk about national security stuff with the Vice President, I'd say that it's probably fine for you to buy weed or whatever.