two options:
1) with our phones we can use them out of the country for a nominal cost/wk/month etc. especially if it is for text messages only. Our phones don't incure any extra charges for Canada or mexico.
2) garmin inreach. Uses sat service (Iridium network) and you can set up a list of people you can text and it is also possible for them to text you. And since your off grid it works for SOS or emergency extraction if worse comes to worse.
It will work anywhere in the world. We've used our from above the artic circle in Canada to the tip of south america, all over europe and asia.
And you can allow others to at least track and see where you are at.
works with bluetooth on your phone if needed to to speach to text instead of the inreach "keyboard"
however I don't think the inreach will work for the two factor authentication app's.