Yeah the pixelization came from the 'nearest-neighbor' filter in Godot. I might experiment and see if I can improve the quality when it zooms out but it might just be an artifact of that we have to live with. I've never tried zooming before like this so I'll have to investigate a bit more!
Definitely planning to add more to the game, with the Eye of Greed at the very least. Really appreciate the feedback! Thank you for playing!