Hey Joe, congrats on finishing the jam and completing your first game! I really like the idea here, merchant sims are super fun. Three quick pieces of feedback for you:
For your next game, definitely look into getting some sound effects! Sound is the most bang for your buck you're gonna get on game feel. I nice sound effect on buying and selling, or starting your ship from a standstill would be great! I think you could probably lean into a sound effect for the ship moving while you're in a planet, but once you get to space cut the sound out.
I think you should start the player inside a planet where a shop is already. You don't start with the map open so it might be a little confusing what the player needs to do at the start.
It takes quite a bit of dev time, but an in game tutorial walking you through the process of buying and selling would be great too! Systems games like this really live or die depending on how well you teach the player to play it. My GMTK23 entry was a merchant sim and I had the same problem, my systems worked but I didn't teach them to the player well!
Awesome job, can't wait to see more from you!