Absolutely!  You can add up to a cup of add-ins to your buttermilk pancake batter. Because you want to avoid over-mixing your batter, it is best to fold these in when your flour is halfway incorporated rather than waiting until you've already mostly combined your wet and dry ingredients. You can also skip the mix-ins and instead top off your pancakes with whipped cream or blueberry sauce, instead. Or do mix-ins and fancy toppings, I don't judge!