i guess you could use a smart tv as "dumb" output only by using the HDMI input and making sure it doesn't connect to the internet (to be able to take screenshots and report them 😀 )
but yes it's ludicrous how anti-consumer the whole smart tv hype is, apparently one reason they're relatively cheap is that companies subsidize it for the adware/spyware on it, so there's no competing without "smart" functionality
I feat that's what I'll have to resort to, I was also researching taking out the panel and sticking a pi into it, but it seems like it''s very closed proprietary tech they have on their devices.
interfacing directly to the panel would be incredible, definitely a neater option if possible ! but you're right if it's not stock eDP/LVDS then it's going to be a nightmare to figure out a way to drive it