I really wish someone would nail this for consumer phones. I'm coming up on a year away from home in various countries and the constant sim swapping is beginning to get annoying.
I actually bought a dual sim phone so that I can keep my Australian sim card in for 2FA security sms messages (etc).
Before someone suggests it, Google Fi is US only, unless you want to arrange for a reshipper (and even then, I'm not sure if it works).