Anyone who knows networking could detect new device connections on an open network they set up.
assuming that it will connect to your network. if it connects anywhere else, good luck to figure it out. at that point you can throw a laptop with capturing all nearby wifi traffic and hope you somehow recognize the TV if it appears among the possibly dozens of other devices
I guess giving you less control over your device is an improvement for them, otherwise their service wouldn’t be obliged to destroy self serviced phones