I don’t really like Apple, but once in a while they do the right thing. This comes from the App store’s new labels on apps.
Signal just has “Contact info” under the “Data NOT linked to you” category. This is just the phone number + contact discovery.
UPDATE
There’s another post adding telegram here. This is what it looks like:
The difference is that phone numbers are tied to your identity, while email addresses are not (at least if you use an email service that doesn’t require a phone number).
Signal has mandatory phone numbers, matrix has optional ones.