I think this game would have benefitted from two improvements: one, scale it up using Godot's standard approach by defining the resolution in the project settings, but then setting the window size to large than that. I think probably your resolution was a tad too big, so the scale that ended up happening was small or non-existent. I tend to set the resolution to 320 x 180, then the window size to 1280 x 720. It's not perfect, but it seems to fit on most screens decently well and still have enough room for players to see most of the screen at once.
Secondly, some of the art kind of blurred together due to the stippling or the dithering. Over-dithering can distort the look of an entire piece, making the art look messier and harder to read. I find dithering to be powerful when used in moderation.
Both of these things are actually pretty minor to me, just thought they'd be helpful for you.
Overall, the game was pretty complete and fun! I'm very impressed that this was your first jam, genuinely very good submission for that, and I really hope to see more of you in the future!