Ask HN: Few question about monetarization of flutter apps

Dear HN,

I took some vacation from my studies to focus full-time on some app I am building. I am using Flutter for this (so far quite pleased with it) and things are going smooth. Also my pricing strategy and how to monetize become more and more clear. However, I am still a bit scared by some open questions:

1) How mature is flutter in its handling of in-app payments? My scenario is simple: User can make a one-time approach and then use the complete features of the app. Is it mature enough to handle the above scenario in flutter only (= no plattform-specific hackery)?

2) Is it possible to have local-only data storage despite having in-app purchases? One selling point of my app is that data is only stored locally, so I would love to extend that claim even to user identities. Also - to be honest - local is simpler than distributed.

3) Should I decide to put up a database with user id's and their purchase status somewhere - what would be a good approach? I am looking for low price, low mantainence and I don't care about configurationability, since my use case will be fairly common. Firebase seemed like a good option, and I have some experience with Amazon Services.

I would be glad if you could help me out! And thank you for reading. Happy Hacking :)