You'll want to use Marketing activities as your root folder, and set the type as "Program" as well, to ensure that you're getting the list of programs. If you have workspaces, you'll need to do this for each workspace as well.
Hi Aaron,
Browse Folders ยป Marketo Developers
Can only return a max of 200 per call. If you have more than 200, you will have to use offset and call multiple times.
-Greg