Most profit on Google is coming from search ads. It is more than twice sum of Youtube and display ads.

Yup, so still an ad company.

Signal requires phone numbers because of taking care of users' privacy. Signal's choice to require a phone number is due to storing a contact list on a local machine to protect users' metadata. And PGP is never as secure as Signal or Other Encrypted Messenger (WhatsApp). Many Cryptographers blamed about weak security of PGP (https://latacora.micro.blog/2019/07/16/the-pgp-problem.html, https://latacora.micro.blog/2020/02/19/stop-using-encrypted...., https://blog.cryptographyengineering.com/2014/08/13/whats-ma..., https://blog.filippo.io/giving-up-on-long-term-pgp/) and even Edward Snowden doesn't use it now (https://twitter.com/Snowden/status/1175437588129308672).

Why wouldn't signal be able to store local data without a phone number? Your argument seems like a red herring.

They could also just ask for an email, like wire does.

Edit: or generate a UUID type random string for each new device.

This is because unlike Signal, the wire store user contact is on the server. (https://www.vice.com/en/article/gvzw5x/secure-messaging-app-...)