The App Store will reject client apps that allow zapping of individual notes and don't integrate in-app purchase. What seemingly can be allowed is zapping of profiles (not zapping of notes). So somewhere between the two is where the App Store draws the line. Comes down to perceptions of "purchase" versus "transfer".

For PWAs this does not apply, zap whatever you like. Though PWAs on iOS face a lot of UX limits due to lack of access to the native APIs. And you have to design them to also work as not a PWA (mobile web).