I just got some Boras maculata, they are so tiny, you could probably handle 20 of them in a 10 gallon. I'd get at least 5 though. They would probably be fine with a dwarf gourami, I don't think the gourami would catch them.
depending on the temperment of the individual gourami, you may find them harassing them to the point of exhaustion then kill them. Some are micropredators so darting away quickly once or twice will not end their chase.