I've done the same! It's impossible to buy dumb TVs nowadays, but you can always prevent them from connecting to the network.
Thank you for the detailed response! I'm going to give it a try! This will be a step up from OpenWRT on a cheap router, I'll bet!
Unraid is a great option for anyone, but beginners in particular. It does, however, cost money and isn't open source.
Do it, my friend. I took the leap ~5 years ago and have not once regretted it. You're right, you have Wine and Windows VMs available, if need be. But, honestly, I bet you end up replacing those work flows with better ones within Linux before long.
This is the correct answer if privacy is your priority. They're not particularly cheap, however.