All data-block types should already work fine in regards to making and storing asset data.
But only few data-block types support drag 'n drop as assets.
The following drag & drop operations should be supported:
- Drag object-data into 3D View
- Drag data-block into Outliner to assign (material, object-data, etc.)
- Drag data-block onto data-block selector or pointer search button
- Drag scene into window
- Drag text into script editor
- Drag image into image editor
- Drag node-tree into node editor
- Drag animation into dopesheet action editor
- Drag animation into NLA
- Drag media file (image, video, sound, text, etc.) into VSE
- Drag movie/image into clip editor