There is enough logging in iOS to show when your extension loads and unloads. Your extension can't be too large or it will not load - and that is logged too.

Xcode 12.0.1 has a Persistent Token Extension template. Note that extensions are limited in size. The exact size varies but is 5-6Mb Be careful about the frameworks and libraries in your extension. If your extension is too big, an error will be logged.