More than that, in theory an opaque handle would also do things like statically prevent a handle taken from one array from being used to access a different array. I feel like this should be possible in Rust with type-level shenanigans (e.g. GhostCell).
this is possible in rust, albeit with a lot of shenanigans. See this article where someone made a GC in rust where the external references are bound to a specific GC via a unique lifetime: https://kyju.org/blog/tokioconf-2026/
