The best I can recommend is probably projectors. They seem to be the last bastion of non-smart/internet displays with large screen sizes.

With respect, there really aren't non-smart TVs. I searched when I upgraded and the best I could do was the LG C series which has webOS as it's platform but didn't require me to connect to the Internet to start using it. It let me skip all connection options after selecting the basic audio and picture display settings. The webOS is the default home screen if you start without having an active HDMI input but it mainly shows input options and other settings. The rest of the items are default apps which are non-functional with the home screen stating "Connect to Internet to access smart functions".

Not sure what you mean by "seek access through open wifi" but on my TV once I declined Internet connectivity it hasn't requested access after giving me a warning that firmware updates wouldnt be available through internet. I also have Raspberry Pi that works as an internal DNS and ad block for my home network and I haven't seen any pings from hardware other than the ones on my networks approved list (tracked by MAC address) The TV has a USB port so manual firmware update is possible if you want that. It has also never requested access for Bluetooth. I'm not aware of HDMI providing Internet connectivity so I can't make a statement there other than my TV hasn't requested anything of the sort. All of the connectivity goggles are off in the TVs settings.

Unfortunately the ship for non-smart home TVs sailed a long time ago. Especially if you want quality 4K panels. There might be a shot at some cheaper ones but those will have subpar panels. The downside has also become that most cheap TVs now depend on the "smart functions" (aka ad revenue) to subsidize the cost of their low prices.