The events that happened between the ending of Space Adventure and the opening of Pinkfong Wonderstar might've gone like this.
Pinkfong travels to Staria only to see a bunch of aliens trying to explode it. The spaceship is destroyed by one of the alien ship's laser beams. The aliens were going to destroy Staria, and no family member of Pinkfong was found. All Pinkfong finds is his old star Pio. He decides to use it to travel to Ocean planet, but it's not there. Pinkfong then starts to feel lonely. He then decides to look for friends throughout the universe, and stumbles upon Hogi's planet. He was in awe of the landscape and scenery. He sees Hogi's house, and goes down. He crashes on his house and the rest was history.
Before you start ranting on this, this is just a theory! Chill.