OP, it may help to understand why
people worry about puppy nutrition so much: there's not much room for error. Screwing up the nutrition during growth can have permanent bad effects on the skeleton for life -- even creating deformities that can't be fixed.
You're probably thinking "but I'm buying good kibble, so how could I screw up his nutrition by just adding some meat to it?" Here's how:
Large breed puppy foods are formulated with very specific calcium/phosphorus, ash, protein, and fat ratios for slow, steady growth. Meat adds phosphorus. So if you take a balanced kibble and then add a bunch of meat (= a lot more phosphorus), you're throwing off the critical calcium/phosphorus balance that the kibble was designed to achieve. Now it is no longer balanced for optimal large breed growth!
If you don't want to put him on commercial raw because it's so expensive, and you really want to do it yourself, then as a novice, you really should be using NRC guidelines and a spreadsheet tracking micronutrients for your puppy --there are some experts here who've been doing it so many years that they don't need to do that, but for regular folks just learning, it's pretty important.
Monica Segal (a respected nutritionist and author) will do consultations to come up with a balanced puppy formula if you want homemade that complies with NRC guidelines -- monicasegal.com, but it costs about $400: