You most certainly CAN use HDMI inputs without Internet access!

Interesting thought, but I recommend a small linux PC over HDMI instead.

Uhhhh, apparently not THAT “factory reset”, unless it’s applied enough updates that they got wise to it? Good lord

The only correct way to use a Roku TV is to never allow it access to any network.

Or factory reset it and use it as a TV (never allowed on a network after) if it’s too late for that