I looked over your photos and those seedlings look like the Ground Cherries to me. Mine are just as tiny. It is hard to believe that these are going to grow into mature plants with fruit. Take a look at the slug eaten leaves of my young Rhubarb plant. I guess the leaves are not toxic to slugs. Do you have a problem with slugs there? They are terrible this year here. Do you think those strange plants around the Rhubarb are the Strawberry Spinach? I did put labels in the garden, but they have vanished. Back to slugs. Here is a video about one gardener finding that he had a problem with them.