I do prefer the version that doesn't use SUBST_CMD on Cargo.toml..

I wonder if there's any point asking upstream if they'd consider
making releases of the dependencies; it can't just be us that has
problems building packages from git checkouts...

btw, to build this outside of ports, "pkg_add py3-pipx; pipx install uv"
would be the simplest way to get working binaries (assuming your
datasize limits are high enough for rustc; 3GB isn't enough, 12GB
is, I didn't try anything in between).