I'm working on a ISO-29148 aligned spec standard with formal modelling baked in. It's meant to sit above the code with types, contracts, proofs and other objects that lower mechanically into code and/or are deterministically verified.

I'm targeting Rust primarily but my goal is that any language could sit under it via an integration layer.

https://github.com/agent-ix/quoin

The first public version of the formal specification standard isn't available yet. Pushing hard to get it out soon! But Quoin ships with an earlier version of the spec standard. It features derived property tests, which was the POC for fully adopting a formal-spec-to-derived-formal-verification ecosystem.