A loose idea I had for his kinda voice is something both sidekicky but not? Vaguely something along the lines of Corphish from the mystery dungeon anime or a less harsh version of the eng dub Monokuma from dangnrompa. See what I mean? That's just the idea I had, though. If you think your version will do him better justice then go for it~

Line direction suggestion: The first line is where Gugelpluf is in a spaceship and looking out at a view of the planet Terraforma, a little in awe at the scenery. Second line is confidently spoken and is where Gugelpluf is being looked at as if just a token sidekick character but then retaliates in a very... Shounen protag kinda way, if that makes sense? Third line is spoken as a response to Sjal yelling that nobody should leave until they finished what they came to do. Hope that helps as some direction if you're a bit stuck~