I bought a fairly dumb tv. No camera or microphone. I do have an Andriod based streaming box that has a microphone on the remote. I keep the microphone turned off in Settings, for what that’s worth. I kill power to the TV and Box by turning off a strip plug when we’re not using it. I’m wanting to build my own linux+kodi based streaming box one of these days. Might do android powered box but it would be a dev droid version not a google tainted version.
Something you might want to be aware of, with the proper electronics attached, a speaker is also a microphone. They have had this technology for quite awhile now. I have used headphone speakers as electronic mic pickups on acoustic musical instruments like guitars many times when in a pinch and needing a local mic right away.
But you are on the right track towards a work around there. Have you considered a Raspberry Pi for that? They have all the needed software available for your Kodi project. :)