A bit of OT, but I have four iPhone 5/5s/SE (the SE is peak design and form factor, fight me) lying around that I use strictly as offline devices for things like saving data from my heart rate monitor, controlling my action camera, doing voice/field recordings through the 3.5mm connector – stuff I'd prefer never to leave my device (or data that should be open to user control but requires an invasive app to work, I have very few apps on my daily driver).
These devices are are small, snappy and powerful enough in 2025.
I am going farther offtopic, too. I have removed the radio on Samsung Galaxy IV device† and they still work. I don't know if that is possible for iphones, just throwing it here.
† I don't have the skills to reverse the process, though :)