I have a paid app on appstore, is it possible to offer the users who bought it a different app, and pull this one from appstore?
We did this several years ago. We implemented a system to do it and it's a little complex. This is not code to use, just an overview of generally how we did it. You'll need to refine this for your exact usage.


Implement a shared "Group" directory to store some preferences in, or iCloud shared KV storage for both apps (on the same key!)
In the Pro app, store something in a user defaults file or iCloud KV, even just a single bool for "is pro"
In Free app, also implement reading/writing to the group/iCloud
Implement a free in app purchase in the Free app to unlock the Pro migration.
In Pro app, set up a dialog to tell users they must download Free app and redeem the free in-app-purchase to upgrade. They must not delete the Pro app until after they d/l and redeem. (Here is where the iCloud shared storage is better, it's available right away to almost all users even if they delete the Pro app first.)
When they download and start Free app, check the shared user defaults/iCloud for "isProUser" or whatever you call your key, and then unlock content. Or maybe show them the free IAP on your content purchasing screen (that is hidden for non-Pro users).
Deprecate the Pro app in the future. Some users might not update, or they mess it up. Hopefully customer service can help with promo codes.
After they update, save a key for "hasUpdated" or something to not show the "upgrade" dialog again if they reinstall; or do but tell them to "restore purchases".


The pro users will have to upgrade 1 more time to get the version that will write their keys to enable the free upgrade.