How can I use 2fa with no stable phone number

I'm traveling the world as a digital nomad and I have become incredibly frustrated as I am locked out of many accounts I own because I no longer use the same phone number, some of which have cash balances associated with them.

It seems like these services treat your phone number as some permanent identifier which seems nonsensical to me.

The two suggestions I've heard are to use google voice or authy, both of which then rely on having a stable, and I think US based phone number, so have the same exact problem.

So is the message from every service that uses 2fa that the service isnt for you if you are moving around and don't have a stable phone number? Or is there something I'm missing here?