But how many hours of video playback?

I haven't done this in a while but when I used to travel I'd get a local SIM and then put my home SIM in an old Android phone. Since the home SIM was roaming (expensive), I'd turn off data, I just wanted to receive calls and texts.

It'd usually last around 2 weeks with data off. I imagine an iPhone would fare even better.

ikr, it had amazing camera and ran the latest linux kernel /s