Couldn't you get around this by e.g. having a JWT auth token be a part of the webapps insalled url? And then if local data is missing, use the token to fetch it from a backend store? That's how I would solve it at least.
>>djxfad+(OP)
This doesn't feel like it's a great idea but considering the implication of your webapp forgetting stuff, I'm not sure of a better option.
>>djxfad+(OP)
1) The people who are really caring about this are trying to avoid having the data be stored on some server also, and 2) so are you claiming Apple got this wrong?... Like, their mechanism here sounded pretty sufficient to me.