Redirections inside your app is always possible The implementations on the web and on mobile are not too different in much respects - so you can use existing widely used web apps and their logic as examples.
The official WP plugin above has a lot of logic in the api and oauth classes which you can just copy for your app.Additionally, if you would like to go that far, it also has a setup wizard which allows creation of oAuth clients for connecting individual installations to users’ own creator account at Patreon. But you seem to be interested in offering benefits to your patrons only so your case would be simpler.
I made a thread with a collection of interesting topics which different types of applications were discussed - including offline apps. You can check those threads to get some insight.