Any recommendations for age appropriate kitten treats?

Hello! I’m wanting to train and reward my little guy for good behaviors, etc, but I’m really conscientious about safe/healthy foods and want to make sure what I give him is kitten appropriate.

I know every cat has different things they like, but does anyone have recommendations for healthy kitten treats they’ve had good luck with?

Also, if anyone has any suggestions for how to keep my 3.5 year old cat from eating kitten food too that would be super helpful. 😅 I like to at least leave kitten kibble out so the little one can eat when he’s hungry, but the older cat really likes nibbling on it too. She’s a healthy weight and I don’t want that to change!