Hi there!
It's most of the actual CMake functionality used by Pamplejuce, my template repository for plugins in the JUCE framework.
It's to help projects built by the template pull in the lastest changes.
Pamplejuce is a template repository. Unlike most "dependencies," when you hit "Create Template" you are literally copying and pasting the code. Which sorta sucks, as people can't get fixes or updates.
For at least the gritty CMake details, there are fixes, improvements and additional functionality being added.
In the best case, as a submodule, you can pull in the fixes and improvements.
In the worst case, this seperate repo will help you see what exactly changed in Pamplejuce.
It could be!
As of 2023, Pamplejuce is still being changed around a bunch, with the goal of being a better and better ecosystem for developers.
That means there could be breakage when you pull.
See CHANGELOG.md.