Re: feature entitlements shared through a shared SSO auth backend and/or Group Container — yes, apps do this. Mostly this is in app "suites" where you can IAP a feature entitlement in one app in the suite, and the entitlement should then become available to the other apps in the suite. (I think the Omni Group apps do it? Correct me if I'm wrong.)
Re: multi-edition shared apps — I'm not sure if this has been done with the App Store in particular, but it's just a combination of things App Store apps can do (basically, moving code out into dylibs, and then marking those dylibs as On-Demand Resources.) I know that this is a common approach to supporting netplay (and especially replay of historical netplay) in competitive-eSport multiplayer game titles on Steam et al, where players need to be on the same exact version of the game engine + netcode to sync (and so those engine libs are downloaded on-demand before the match begins); and where you need an exact ABI version of the game engine to replay a netplay recording (and so that engine lib is downloaded on-demand when you go to replay the recording.)
ETA: looking more into this, I'm finding conflicting reports on whether executable-code On-Demand Resources are currently allowed on the iOS App Store: it looks like the Apple docs say no, and yet some apps (from not-bigcorp devs!) are doing it anyway and getting away with it (and have for many review cycles.) Very confusing. Maybe those devs are part of an alpha-test rollout for executable-ODR?
Re: multi-edition shared apps — I'm not sure if this has been done with the App Store in particular, but it's just a combination of things App Store apps can do (basically, moving code out into dylibs, and then marking those dylibs as On-Demand Resources.) I know that this is a common approach to supporting netplay (and especially replay of historical netplay) in competitive-eSport multiplayer game titles on Steam et al, where players need to be on the same exact version of the game engine + netcode to sync (and so those engine libs are downloaded on-demand before the match begins); and where you need an exact ABI version of the game engine to replay a netplay recording (and so that engine lib is downloaded on-demand when you go to replay the recording.)
ETA: looking more into this, I'm finding conflicting reports on whether executable-code On-Demand Resources are currently allowed on the iOS App Store: it looks like the Apple docs say no, and yet some apps (from not-bigcorp devs!) are doing it anyway and getting away with it (and have for many review cycles.) Very confusing. Maybe those devs are part of an alpha-test rollout for executable-ODR?