How to get a list of graphnodes

My goal is to get a py list of all the possible graph nodes.

I’ve found that in a graph editor window you can open the “Palette” window which does list all the graph nodes. I’ve looked through the source to try to decipher how the palette is getting that data, but I don’t see how it is doing so.

I would love to know how the palette gets that data or if there is a way I can access that data on the palette to rebuild a list.