Your carrier knows the contents (and the metadata) of the RCS message since RCS messages on Androids are routed through Google only when the carrier doesn’t supports it.

Ok that's n interesting application, damn I always have my phone around....

But yes, it would be interesting. Point is, I can't think of how I would work unless you replace your phone message app with this one, and thrust it.

For OTPs you might not want to send them by email, emails are a little less secure than SMS (it's easier for a third party to hack your email than to intercept your SMS)