@m455 it's really hard if you have a lot of dependencies; packaging leiningen took ... many years of hard work
if you only have one dependency and have good build hygiene (like with Fennel) it's not that bad! a lot of the packaging documentation is old and dusty and makes really stupid assumptions about you being an expert at C, but if you have a little help from someone experienced can go pretty quick
https://salsa.debian.org/bandali/fennel/-/tree/debian/latest/debian?ref_type=heads