It would be “best” to make a website that would do the auth loop and present the oauth key to the user to copy/paste into your Application.
Otherwise if your App was doing the oauth loop itself, you would have to distribute YOUR application secret with the app, which is a bit against the rules. Sure you can make your App require users go setup their own clientID and secret but thats a mess for people to do.
Either make a website that lets people go thru the loop then copy/paste out the oauth key.
Or you could make your app login to your website as a separate auth and fetch prior stored oauth keys. So your website would have it’s own accounts system with a linked TwitchID and associated oAuth that your native app could fetch and use on demand.
I think chatty used to spin up a local server and oAuth loop would loop back to that but I think they dropped that when people get iffy about distributing secrets.