These are features that fit the "Purpur" theme, or have been requested for Purpur, but work better as a datapack.
What determines if something should be a datapack is if the feature is data-driven. You can kinda look through repos like misode's mcmeta or use a tool to decompile minecraft yourself to see what is data-driven.
There's a folder in the first directory, named data - everything in that directory is modifiable by datapacks.
