It's an intriguing idea. Having experience with software but almost none (only hobbyist) in hardware, I imagine it'd require a strong type system and mathematical foundation. Perhaps something like Agda, a language that is a proof assistant and theorem prover, with which one can write executable programs. https://en.wikipedia.org/wiki/Agda_(programming_language)

I wonder if an escape hatch like Rust's unsafe{} would be enough... a hardware{}. The real complexity likely lies in how to integrate the synthesis tools with the compiler and debugger. The timing model. A memory model like Rust's would certainly aid in assuring predictable behavior, but I'm not certain it would be sufficient.