such a promising setup for a game - both narratively and gameplaywise - really hyped by the idea. and your physics system seems rock solid. I can't wrap my head around why you would not implement sound in a pinpall game as like the second thing you do, but I guess we all have different priorities (I started my game with looking for free mechanical keyboard sounds ;-) )
I came across a couple of submissions that used really powerful free pixel art tools for generating planets and galaxies and I thought, why not let you know about them, maybe there's something for you in there:
Deep Fold's Space Background Generator: https://deep-fold.itch.io/space-background-generator
Deep Fold's Pixel Planet Generator: https://deep-fold.itch.io/pixel-planet-generator