Those huge plugin files result from Rust duplicating libstd into each plugin at link time when crates are built as cdylib or staticlib, and you can prove it with cargo-bloat or by inspecting DT_NEEDED and symbol sizes with readelf -d and ldd.

If you control the build, force shared std linking with RUSTFLAGS='-C prefer-dynamic' and crate-type = ['dylib'] so host and plugins share libstd and accept the need for matching toolchains, or switch to a different plugin model like compiling to WASM and running modules with wasmtime or exposing a small C-ABI shim into a single shared runtime, and use strip plus LTO for quick size wins.