If you have a particular variety in mind, maybe search by common name. I'm not sure if you have them growing or are buying from the store... It appears that some members of the physalis family are potentially dangerous and others may cause illness while some are edible, like tomatillos.
However, I can't find any varieties on safe/not safe lists. If it's not edible for humans, it is not likely edible for dragons. Not being familiar with them, and seeing they have suspicious cousins, I would be hesitant to say it's ok.