Simplest option is probably speak to sales staff & specifically ask about the set up process. It might be worth phoning a couple of reputable TV vendors as they may have more understanding than the spotty herberts in the sheds at the local retail park.
I last bought a TV outside of your preferred time frame but back then Panasonic made, what for my needs, was the best panel for the price & didnt insist on having internet in order to set it up (no idea whether this has changed with current generation models)
It doesnt help with your hdmi concerns, but what about blocking the TV at router level or restrict it by putting it on VLAN/guest network then disconnecting it from the internet forever once set up.is complete?
Go into this completely blind - do not watch the trailer, do not read about it first, just take a deep breath & enjoy the ride