A very simple proton sms app that I can log in to my proton account and have it upload all incoming sms automatically (and instantly) to a file on my proton drive (or maybe a note on proton pass).
We all need a phone number tied to our identity wether that be for banks that only allow that form of authentication or other government related tasks.
With that kind of app, we could leave one phone tied to our identity permanently at home, and access received sms on any other device through our proton account. That way we would not have to be constantly broadcasting our location to our phone service provider (and potentially the world).