In the mixing bowl with the avocado, combine the drained pineapple, half the red onion (or less to taste, depending upon how strong a flavor you want,) half the radishes, juice of half the lime, and season with a pinch of salt and pepper. If more liquid is needed, add some reserved pineapple juice. Place in refrigerator to chill before serving. In a small, dry pan over medium heat, lightly toast the pepitas, moving the pan to prevent burning, about 2-3 minutes. Remove pepitas from pan once browned and aromatic to prevent further cooking.