I do the vast majority of nursery pick ups. If there has been an issue or if ds has done something new I get told but otherwise it's a general "all went well today" if I ask what they ate for lunch and how much ds ate they tell me but I don't tend to ask as I don't see that it makes any difference to the rest of the day.
If he's hardly eaten any lunch I offer him dinner exactly as I would if he'd eaten a huge lunch, I don't worry about his food intake, I believe that if he's hungry he'll eat, we give him varied balanced meals, we can't do more than that.
Dp often asks me what ds has eaten for lunch and how much he ate and I say it don't know, I didn't ask. Aibu not to really concern myself with what and how much ds has eaten?