I am a regular breakfast eater. Some mornings I just want oatmeal but I don't have any overnight oats ready. So I keep packets of plain instant oatmeal in the pantry. By using plain packets, I get the convenience of instant oatmeal but I can add-in my own flavorings.
This weekend, I used apples and walnuts. I sometimes skip the nuts and add cinnamon. Another favorite combo is a bit of maple syrup with pecans. Raisins or other dried fruits (no-sugar added) are a good option as well. Unsalted, low sugar trail mix makes a fun mix-in.
Fun for kids or grandkids, make an oatmeal mix-in "bar".