I have an iPhone 13 as my phone

I also have a cheap ZTE Blade that I turned into an mp3 player because it has a microSD card slot. I just removed every app I could, installed Musicolet, and loaded a card with a lot of the music I have on my pc.

It doesn’t connect to any cell network and rarely do I connect it to my wifi. I’ve been looking for some kind of schematics so I can disconnect anything that could connect to a cell network and I’d also like to disconnect the microphone and camera too. I just want it to work as an mp3 player with an expandable card slot and only go online if I choose to connect to wifi.