Could connect the tv to the guest wifi network which would prevent it from accessing your local network. Plug in an android tv box of some variety and connect that to the network and you can cut the tv off f4om internet entirely. If you set the pihole as your primary DNS on your router then all network traffic goes that way anyway. Set up google as a secondary in case your pihole goes down. Or configure a second pi hole for resilience and set that as the backup.