Oh, that sounds annoying. I also bought an SE 2016 128GB as "Offline-First" / de-Appled device. I think what I did was just signing in to App Store, not fully adding my Apple ID to the device. It now serves as a time capsule, has all the classic apps like Doodle Jump, Fruit Ninja, MiniMetro etc and some resource-light open source apps like CoMaps, fileexplorer with connection / offline sync to Nextcloud. Jailbroken via Palera1n (Think I didn't have to approve install any certificate)