Televisions are terrible at text entry, so Playarr does not ask them to be good at it. A television shows a short code, you approve it from a phone or laptop, and the device is signed in, the standard device-code flow, served by your own server.
The hosted Playarr service can also broker the very first handshake between an app and a server it has never seen. That short-lived record holds only the device secret, the server addresses you chose, and a single-use device code. It never receives a password, a browser token, or a refresh token, and it expires within minutes.
Once linked, the app talks to your server directly. Nothing routes through the hosted service afterwards.