Interesting game! I like that old DOS look with the 3D renders, definitely captures that 90s vibe. It's an interesting idea to have the upgrades physically stick onto your ship, as far as I can tell though their positioning doesn't matter, quite like the idea of having the player decide to turn their ship so they can catch an upgrade on the right spot! I also found the number of types of upgrades quite overwhelming and they kinda blended into one multi-coloured mass, might be better for visual clarity and decision-making to whittle them down to 3 or 4 and dole them out with less frequency.
As far as the bullet hell gameplay goes, I think this game suffers from the shots being way too small and fast and not having separate colours for player and enemy shots. A bit of damage flash on the player/enemy models would also do a lot for visual feedback. Think you can afford to make the shot sound effects beefier too, though given the auto-shooting that might be tiring for the ears. This might be a personal preference of mine but I also wonder whether this would work better as a shoot'em up, as in the player is confined to a screen they can zip around in and the enemies fly in from the top or right?
With a bit more work post-jam this will be a neat arcade experience!