We really need some straightforward way to carry a mostly-wiped phone, and then download an app, input credentials [0] (stored in your head), and have everything [1] downloaded from a cloud server and ready to go.
[0] since I'm spelling this out, one of those credentials should be a passphrase such that the server doesn't have access to your data
[1] modulo data/apps you actually want on a phone in a foreign country, of course
Interesting idea. But, in your vision, what would be the main difference between this approach and actually wiping your device, install just some basic apps you need during the travel (e.g. airline's app for the boarding pass and flight info) and then restore from your cloud backup at the end of the flight? Main difference I see is that Apple/Google wouldn't have access to your data, but this only makes sense if you're not using their services to start with.
Does iCloud not blast you with a bunch of "2FA" hassles the way Google does? That passwords are no longer complete account credentials makes this approach a non-starter, unless you want to come up with some protocol with a trusted person who stays home (with access to your account) and can perform those verification steps for you.
Even so I would still be worried about the nonstandard behavior of activating a new device in a foreign country causing my Apple/Google account to get straight up locked by their arbitrary and capricious "security" systems.
Passkeys are stored in your Apple Keychain. I don’t think you have to go through 2FA if you use a Passkey with Google.
I can throw my iPhone in the ocean, go to the nearest cell phone store/Apple Store and log into my Apple account and you won’t be able to tell the difference between my old phone and new phone - all apps, data, icon positions, passwords, photos, settings, bookmarks, history, messages etc will be restored
