Yes, pretty much every good library I came across referenced Meeus' Astronomical Algorithms [0] book and formulas. Those were a bit dense for me to fully parse, but Dr. Louis Strous` page [1] on finding the position of the moon helped simplify it for me (although that implementation is less accurate, I think).

The algorithm in Moontool for Windows [2], which Tiny Moon is based off of, is based off of Meeus' algorithm.

0. https://www.agopax.it/Libri_astronomia/pdf/Astronomical%20Al...

1. https://aa.quae.nl/en/reken/hemelpositie.html#4

2. https://www.fourmilab.ch/moontoolw/