> I wonder if there is a subset of Rust that can be extracted someone into a new, minimal language with the core benefits.

That is basically what Val aims to do:

https://www.val-lang.dev/

It has Rust-style ownership to guarantee memory safety, but without the complexity of lifetimes.

There is still a borrow-checker-like component, but I believe it should be much simpler than Rust's (see e.g. "method bundles" and how they are called).

Still in the research phase. It is an open question how well this approach scales.