Last I knew they support firmware update via thumb drive too (mine does) so if there’s some critical fix you need you’re not locked out if you don’t want to hook it up to the internet.
The "Applicable Products" were from 2017/2018, at least for the few i checked. Is this still possible with their new models?
Yes, you can do it with any of the models running Google TV.
Also, I thought I heard "commercial" TVs are dumb TVs. Although, I haven't heard much about those.