It’s appletv unless you’re willing to use a custom sbc with a taped together third party android version.
I don’t recommend the latter option because it fucking sucks and you seem like a psycho to others who may use it or watch stuff with you.
You can just host jellyfin from your pc (or a server in your closet) if you wanna get away from streaming services and it works good with either option.
I want to be clear as day that you cannot get a privacy friendly experience from any Android streaming device unless you load it yourself and make sure it’s something like the lineageos Android tv stuff linked by another user.
It’s probably worth it for you to put into words what you’re trying to accomplish, being as clear and explicit as possible.