Plus, “initiate deletion of their account from within the app” sounds like the app can simply link to whatever account deletion functionality you have on your website.
if you provide a good and easy sign in functionality from your app, through native UI and the like, then you should be able to provide the same functionality for deleting that same account. That is at least what we have recommended one of our clients, but that client is also a public transport company, so they can't afford to be in gray area where the app is either rejected or taken down.