In a “front end no server scenario”
You can only use implict auth.
Or your front end talks to a server and the server does all the token schnangians.
That would be optimal to avoid the streamer having to do something every 60 days (or sooner)
In your current scenario you can only use implict auth.
As you cannot/shouldnot store your client secret in the desktop app for authentication purposes, as thats leaking your client secret.