You are asking the good questions.

So I looked into getting an Inmarsat satellite phone with global coverage.

Basic talk text but no data. All Inmarsat to Inmarsat calls are free.

But here is your problem, without A US primary carrier phone and email from participating email provider you can’t open an online account even for things like strike.com or gunbroker.com etc

Even using a VoIP phone with a masked passmail.me email will get you rejected!

I have proof…