I would also really like to check in the database what games are missing from my collection, and which games are missing on the database.
Is there a feature request for Launchbox? This would be one of my top, if not the main one.
I also got them.
Is there a way that I can add them into the handheld category?
EDIT: Yes there is. Right click, edit, parent tab, tick the handheld box.