Can we bundle our app with our own version of SQLite with extensions that we want. Yes, and you should do that. The version that Apple includes depends on the iOS version (see https://github.com/yapstudios/YapDatabase/wiki/SQLite-version-(bundled-with-OS) for a table). If you use the Apple version, there's a danger that your app will break after an iOS update, or will not function on an older iOS version that you are still trying to support but don't test on as well as you should. I was caught out by the latter issue because the sqlite in iOS 14 doesn't support on conflict without a column list.
Topic:
App & System Services
SubTopic:
iCloud