Is that not most if not all smart TVs today? Basically nearly every TV made and sold right now?

privatize the profits, socialize the risk and debt

also/or seperate rights and responsibilitys

but if the host OS is already comprised, what is the point of sandbox inside of it?

Maybe we need secure attestation for sandbox to be protected against compromised host :)

It does sound hard, and might need to employ homomorphic encryption with hw help for any memory access after code has been also verifiably unaltered through (uncompromised) hw attestation.