It takes about 5 minutes to make a nix expression for a "./configure && make && make install", with most of that time being figuring out the dependencies and calculating the checksum of the tarball.

Example:

https://nixos.org/nix/manual/#ex-hello-nix

For any standard build tools (cmake, scons, whatever) it's just one extra line. Applying patches is one extra line. For a non-standard workflow, you can supply a shell script for each step (unpack, configure, build, install, &c.). so it's just however many lines that is.

I've had zero issue getting any source-based third party stuff running. Binaries are a pain, but that's always true if you aren't running the exact distro that the binary was built for.