If the TV has no Internet connection, the mic is useless. I use an Amazon Firestick in developer mode connected to a network that uses a P-hole and other mitigation efforts to keep all the nasty tracking, beacons, etc. minimized. Nothing is 100%, but we can come close. What I'd like to see is a browser that doesn't allow scanning of fonts, etc. There has to be a way to perhaps fake what they can see and poison their data collection.

Better check for more microphones. They are like potato chips. Bet they can't install just one ;).