This was a really fun game. It took me a few attempts to understand what I was doing well enough to beat it, but I did eventually manage a full run and beat the game. Overall, I really enjoyed this game, and one of the highlights of this jam. In terms of suggestions I'd make, I can think of a few, but they're all fairly minor.
One is that I feel like the controls could have been simplified. There are a lot of keyboard buttons needed for this game, and I feel like it could and should have been reduced somewhat. One would be to avoid having to manually refuel the ship. I'd either have just one fuel value (the one the player carries), or make it so that hopping into the ship automatically fuels the ship as much as possible. Even just this one change I feel would help make the game feel more approachable.
I feel like the game could have done with a main menu. There is the story screen, but having an additional main menu would have been nice to see. You could then put the difficulty settings on there instead of the pause screen, which I assume would be easier to handle, since you aren't applying those settings while in the middle of the game.
On the topic of settings, the pause menu feels excessive. Having individual sliders for every possible sound effect is more than I think is necessary. In my game, I just went with two sliders: one for music and one for SFX, which I think was good enough if you balance the audio well enough yourself. (I handled this in Godot using audio buses, which makes it fairly easy to implement). Similarly, the difficulty sliders are hard to grasp. The descriptions are fairly vague, and could have used more clarification. While I think sliders are a nice feature for those that want it, I think having something like two or three balanced presets would have been nice for people who don't want that level of granularity. Something like "Easy", "Normal", "Hard", and "Custom" could have worked.