I am trying to create an HDA that produces a cabinet with drawers. Since I want the drawers to be openable in UE4, I need them to be separate static meshes than the cabinet itself, but I cannot figure out how to do this.

How can I have an HDA that produces multiple static meshes?

If it's not possible to create an HDA that can be brought into UE4 with this ability, I would be happy with an HDA than can export FBX with multiple mesh components, but I cannot even figure this out. It seems an FBX creates multiple pieces of geometry for each geo node at the obj level, but an HDA is based on a subnet within a single geo node. Am I right about that? If so, how can I create an HDA that creates and manages mutliple geo nodes?

An obj-level HDA can have multiple static meshes, each top level obj with a display flag that has geometry will result in a separate static mesh. For example dropping down two sphere objects in your scene and packaging that up will result in two static mesh components in ue4.

Ah! I didn't realise I could create an obj-level HDA. Thanks Chris!