Here are things I sometimes add to my instant ramen:

While cooking:

• Frozen peas or frozen corn
• Fresh seasonal veggies
• Dried mushrooms (rinse them first)

Before serving:

• Deli meat
• Sliced fish cake. Our local Asian store sells fresh and frozen and they both last a long time unopened.
• Chili crisp
• Nori

I also make pork belly specifically for ramen. I rub it with salt and sugar, roast it, slice it into strips and freeze it in small packs so I have it handy. It cooks up pretty quickly in a frying pan. You can put it in while cooking the noodles if you don’t want to get a pan dirty but it’s not quite as tasty.