They will love that stuff as treats. Just remember not more than 10% of their total daily ration so it stays balanced. Lots of those things you mentioned are sprout-able. I do barley because it had the least mold and growing troubles during my research and is about 14% protein. Wish I could find field peas to sprout. And instead of regular sunflower seeds have you heard of BOSS, black oil sunflower seed? Seems like people find them more nutritious than standard, but I do know they are high in fat. Millet, sorghum, wheat, sunflower seeds, corn, oats, peas, barley... all sprout-able if bought in the correct form. Remember feed grade not seed grade in order to avoid any pesticide or herbicide they might use on things intended for planting.
All my girls are layers, but some of them are hardier/heftier breeds like Wyandotte, Barred rock, Marans... those that are considered dual purpose breeds are the ones that need not less than 18% protein mentioned. Light bodied layers like leghorn will do OK with 16%.
In order to figure out your nutrient content of you listed recipe, you would look up the individual items and mark down all them numbers and in the end you would would figure what ration of each and do some math. For example if I mix 50/50 gamebird feed at 30% and flock raiser at 25% protein then my actual protein content would be 25%. So add them all up and divide by the number of ingredients type thing. But I think you have already decided to do those things as fun treats, so this is just informational.
Curious, where did you get your recipe? I'm not condoning the following link, but sharing for informational purposes to add to your research. With everything, you MUST use your own judgement with the information you have available at the time. If you learn something new or discover it isn't working for YOU, switch it up! We all have different flocks, set ups, and goals. But most of us do understand that nutrition is KEY to a healthy flock...
https://thefrugalchicken.com/organic-homemade-chicken-feed/
So cool that you are doing research and preparing!
I bet you're gonna have a great flock and a wonderful time!
Here are a couple of links with comparison of different breeds in case you're interested...
http://www.sagehenfarmlodi.com/chooks/chooks.html
https://livestockconservancy.org/images/uploads/docs/pickachicken.pdf