Thing to remember; the original manual had bowser listed as a necromancer/wizard that turned the people of the mushroom kingdom into bricks. So his ‘blowing up alderaan’ scene is simple. Line up prisoners and magic them into either masonry, or skeletons that then put on shells (and thus giving you dry bones) as an enslaved undead workforce.
And frankly I would watch that movie. It’d be a fun fantasy sorta turned on it’s head the old 80’s fish out of water thing used to great effect. Also Luigi may be afraid, but he has the natural reaction to being stuffed into weirdland; ‘What the actual fuck is going on?’ Also it’s shown time and again yes he’s afraid. No that does not stop him from doing his job. Easy to charge into danger when you’re all smiles and having fun. Far harder when you’re scared out of your mind and do it because you know it needs doing.
Also this scene has to exist:
Bowser triumphant, apparently having having knocked Mario down a garbage chute/waste pipe/whatever. Then through Bowser’s echoing lair you hear Mario’s voice. ‘Don’t you know who you’re messing with?’ And then as he comes out of a broken overhead pipe and have mario jump down on bowser’s head. "It’s a-Me. MARIO!’