A dog who is not stimulated properly mentally and physically every day with develop unwanted behavior and quirks, and picky eating is a big part of that.
You need to put your foot down and stop spoiling!
And this is coming from an owner of a 'picky' dog!! When I first rescued Pedro he was allowed to free-feed at his previous home, he was underweight, his blood panel came back with deficiencies in every area, and he was boarderline anemic.
It took me two weeks of playing 'tough love' with him to get him to eat meals properly, and two years later, he'll still eat whatever I put down.
You need to ensure that if you are home cooking you are providing a fully balanced and properly proportioned diet ( animal protein : animal fat : carbohydrate : fiber ratio's are SO important!!, as well as proper supplementation! When you cook food, you cook a lot of the nutrition out of it!)
You need to walk him before meals, not after, so that you are meeting his psychological need to travel/hunt in order to find food. You eat first. You then put his meal down for 3-5 minutes. If he does not eat it, you pick it up and he is then fasted until the next meal - no cookies, no bones, no treats. He will start to get the idea, and he will start to eat well.
If he is eating well, then yeah sure, he can have cookies and bones and treats....but he needs to eat well first.
Good luck, you can do it, it's just a matter of whether or not you want to!