Jishnu
I've looked into this before, but it's very tricky to do.
You can easily embed a web view into an app and call it a day, which at $1.5-2k is likely what would have been done.
Instead, you'd realistically need to recreate a large amount of Flarum's core JS inside the app, especially things like the Store.
You'd ideally also want extensions to be able to integrate with the app, too, which would be very difficult for less common extensions.