Email is the messenger you should migrate to

This 'messenger' is called Delta Chat. [0]

It's open source, e2e encrypted, decentralised messenger and for once its doesn't use / require your phone number.

However, I wouldn't recommend this to the average WhatsApp user yet. As it doesn't support other features found in other apps like Audio/Video calls, etc [1]

[0] https://delta.chat/

[1] https://delta.chat/en/help#does-delta-chat-support-end-to-en...