Apple TV 4K uses the A10X, which is ARMv8.0. That's so old that it even pre-dates the true atomics instructions (which are intro'd in 8.1-A). So it'll have to be a pretty heavyweight JIT to adapt ARMv8.3 code to that baseline.

For Apple A11 though, going from 8.3 -> 8.2 is much easier... and doable through a patch on fault method.