Comment by goncalomb

This is the list of possible supported devices right now (USB only):

http://www.sane-project.org/sane-backends.html

But HP is a special case, they provide their own backend (hpaio, open-source) for SANE that is not integrated into sane-wasm ATM.

http://www.sane-project.org/lists/sane-backends-external.htm...

If your device is on this list, it's NOT supported right now! But I do want to add hpaio soon, I also have access to an OfficeJet to test.