There’s no need to make these things Big Tech, so if that’s why you are opposed to it, reconsider what you are actually opposed to. This could be implemented in a FOSS way or an open standard.
So you not trust HTTPS because you’d have to trust big tech? Microsoft and Google and others sign the certificates you use to trust that your are sending your password to your bank and not a phisher. Like how any browser can see and validate certificates, any camera could have a validation or certificate system in place to prove that the data is straight from an unmodified validated camera sensor.
One of the concerns I would have with custom ROMs for TVs is that I think a lot of the image processing magic that makes the image look good on these high end displays is done in some proprietary method that the custom ROM wouldn’t be able to use. Either in software or in hardware.
The magic of the high end TVs isn’t actually in the panel itself as much as in the driving of the panel.