I did something similar and just sent a link to Signal when IPhone friends and family SMS’d me, worked…eventually :) (am on Android)
As an Australian, either.do I. They are in Mastodon and I have pointed out that being in Australia should make them a no go for anyone.
??? Theres a while bunch of loopholes they can exploit without having access to your phone, here’s must one.
https://www.netspi.com/blog/technical/web-application-penetration-testing/why-totp-wont-cut-it/
I do it the way you do it as well but am under no illusion it’s bomb proof.