The sign-in experience is where you’re going to get a lot of friction. Your users are going to need your server address. They’ll have to log in to devices with username/password including TVs unless they have signed in once already somewhere else on the network like a desktop. Then you can set up an Easy PIN code or use Quick Connect, but those are hidden behind the user settings menu.
Is this a repost? I’ve seen this exact same post somewhere.
Anyway, SimpleX may not be decentralized OOTB, but can be made to be since their relays are self-hostable. It should be as simple as spinning up an instance and changing the url in app.