I looked into the iOS issue once, and in the EU at least, it should be possible to add a minimal implementation of the store API to an app, so other iPhones could download the app from an iPhone hosting it.
After discovering the amount of pain involved with that API, I quickly discarded the idea though
Source? I guess you're thinking of long tap → Airdrop, but that essentially shares a link to the Appstore via Airdrop. You're not transfering the app itself.
After discovering the amount of pain involved with that API, I quickly discarded the idea though