Hey np, we do need more people being conscious about infosec.

For the most part, I only use FOSS apps on my phone.

This will probably make you flip your lid, but you do have to sign up with a phone number like Signal.

You can use a disposable number site to complete verification though e.g. https://freephonenum.com/us

(just be aware that you won't be able to sing in with another device without access to that same phone number)