I have one big file with a bunch of useful Geo node setups, I feel dumb for asking, but am I able to group the set of nodes and append them like I am able to with shader nodes?
3$\begingroup$ Hello ! Do you mean append ? If yes, you can do it like shader nodes, in fact if you use the append tool, the GN trees will be located in the same folder as the shader trees $\endgroup$– GorgiousJan 11, 2022 at 21:41
As Gorgious commented, you can choose "File" -> "Append", then you choose your blend file and in the directories you click "Nodetree", then choose "your" nodetree.
After that you can choose it in your GeometryNodes Panel like this: