As far as I remember, you can actually do dynamic linking. But it has its caveats.
Maybe using two different crates, lib-internal and lib-external, where lib-internal compiles to an dylib/so that exposes a C-abi compatible interface. Lib-external it’s just a idiomatic Rust wrapper to that api. It’s a little bit wonky, but I’m pretty sure that it can work.
Not that wonky, it's really a natural consequence of the fact that Rust's stable ABI is the C ABI. Plus you can then use lib-internal from any language that supports FFI to C, not just from Rust.
(Of course, some things just cannot be supported across a dylib boundary, such as arbitrary monomorphized code. But this limitation applies to all such languages; it's why you have "header-only" libraries in C/C++ for example.)
https://wiki.debian.org/StaticLinking#Rust https://lwn.net/Articles/797616/ https://github.com/rust-lang/rfcs/pull/2603
I note that the PR for Rust symbol mangling got merged, but it looks like it isn't the default yet, they are waiting on external tools supporting it.
Of course you can do dynamic linking without the way that I previously described, but that library will be highly tight to a specific version of the compiler. I think that the biggest problem is dealing with product types for that matter.