Nix can do it incremental
U could split it into multiple derivations which get built into one package
For rust there ist the excellent https://crane.dev/index.html project
Or you can also go to the extreme and do 1:1
source to derivation mapping
So for example if ur project has 100 source files it could be built from 100 derivations, the language/CLI tools are flexible enough for that
Don't know tho if there any well working smart nix tools which can make it well working /efficient, in theory it's very possible, just unsure about practicality/overheads