I think the zucchini sounds awesome. Yum! I'd go with minced chicken thigh, grated zucchini, egg (whole, or just the yolk), seasoning, and the crumb as you did before. I think egg inside it would help it to bind and keep it moist better than mayo, but maybe mayo makes a good crumb sticking agent? I for crumbing, I usually use plain flour, then a dip in whole beaten egg, then the crumb. It makes for very mucky fingers, but a good, stuck down crumb.

It's all sounding like a chicken meatball recipe to me, and I'd happily serve that up for DP and I (maybe I'll do it for tonight's dinner!), but you can call it nuggets and just give it to DS if you like.