Signal still centrally collects metadata

Signal doesn't collect any useful data; they've been compelled by court to present all data they have on users and all they know are two time stamps. The date + time your phone number registered and the last day (not time) one of your apps (linked desktop app or tablet) pinged their server.

Source: https://signal.org/bigbrother/

... and requires a phone number to participate.

Because it originated as an overlay of the SMS/MMS network, a text messaging replacement, before everyone was "always online". But that's beside the point as you can now hide your phone number from others.

If you're serious about privacy, ESPECIALLY if you're part of a group looking to organize in a clandestine fashion, you should look into the vastly superior SimpleX Chat.

I wouldn't recommend SimpleX chat, its developed by a Trump-supporting Antivaxxer who believes in wild conspiracy theories, not the kind of person I would put my trust in. Source: https://social.tchncs.de/@pixelcode/114633102552691724

If you're serious abut privacy, ESPECIALLY if you're part of a group looking to organize in a clandestine fashion, you should fund the development of your own secure channels. Don't outsource the important stuff. For everyone else, there's Signal.