Most TV's won't freak out if they lack an internet connection...

If only this was true.

Some (if not most) check for a connection on power up and "freak out" by launching into setup if there isn't one --- unless you run the TV in store/demo mode.

Backing out of setup on every startup is possible --- but it is often a multi-step process that becomes extremely annoying. Basically, they try to frustrate you into connecting --- unless you run the TV in store/demo mode.

I have a lower end Hisense 55" QLED model from Costco (roughly $250) that I run in this "dumb" store mode connected to my own "smarts" that I control.