,buildPlatform = The "build platform" is the platform on which a package is built. Once someone has a built package, or pre-built binary package, the build platform should not matter and can be ignored. (https://nixos.org/manual/nixpkgs/stable/#chap-cross)
arianvp: targetPlatform is only for if you're building a compiler or similar
it's for, like, "what arcitecture will this gcc build executables for"
i.e. you could build a gcc on x86_64 (buildPlatform), that runs on aarch64 (hostPlatform), and produces riscv executables (targetPlatform)