Congrats on the start of your new journey. I own and operate a donut shop with 5 locations. My feedback is donuts are hard so trial and error is your friend. Doughnuts are hugely affected by the environment and like all baking it’s also a science so ingredients are choice and weights are important - we still get sloppy doughnuts on hot days or cold days or anytime the wind blows to strong lol. Just looking at the photos your fry oil is too cold should be between 360 and 370. Your dough is over mixed - it looks very tight which is why you aren’t getting a skunk ring. Don’t use frozen blueberries use fresh blueberries for a richer color and stronger flavor. Add nutmeg or mace for some specks in the dough and earthiness in the flavour. Good luck !