Place the chicken thighs in the Instant Pot. Pour in the chicken broth. Add the soy sauce, sesame oil, miso paste, grated ginger, minced garlic, rice vinegar, and sriracha. Stir gently to combine.
Lock the lid, set the valve to sealing, and cook on high pressure for 10 minutes. While waiting, prepare your soft-boiled eggs by boiling them for 6 and a half minutes on the stovetop, then transferring to an ice bath. Peel and halve them.
Once cooking is complete, quick release the pressure. Remove the chicken thighs and shred them using two forks.
Set the Instant Pot to saute mode and bring the broth to a simmer. Add the ramen noodles and corn kernels. Cook for 2 to 3 minutes until the noodles are tender, stirring gently to separate them.
Turn off the heat. Stir in the baby spinach and shredded chicken. The residual heat will wilt the spinach in about 1 minute. Taste the broth and adjust the soy sauce, sriracha, or sesame oil to your preference.
Divide the ramen among deep bowls. Top each bowl with halved soft-boiled eggs, sliced green onions, sesame seeds, and torn nori sheets. Serve immediately while piping hot.