I am decidedly not a parent, but I do know a thing or two about fiber and nutrition. I've heard that you can blend veggies into sauces to get the nutrition while masking the taste/texture. So if you're making spaghetti sauce, which I don't think is particularly labor intensive, put some tomatoes, cucumbers, carrots, onions, etc. in there (perhaps panfry them first to soften them up though that is, of course, more work). You might also consider sugar, oils, etc. to make it go down smoother. You might dilute the nutritional benefit, but if it's the difference between some fiber and no fiber then it's still a win. In the same vein, smoothies with blended ice, fruit, and sugar have some nutritional benefit to give.

I don't know the first thing about what kind of restrictions on diet being 2 years old gives you, but I know scaseyfitness (on all the different social medias) had some of the most simple, easy meal ideas for people who like to eat more than they like to cook. His focus is low calorie/high protein, but the neat part of cooking is you can substitute with what you have and what you need. That's the sort of thing where you could substitute a custom (pre-prepped) veggie sauce to make sure you're getting a complete macro profile and a bunch of vitamins & minerals. With some prep and planning, you can keep hands on cooking+cleaning time in the 15-20 minute range so you don't have to change your lifestyle to be a better chef.