Excellent mechanics and game design, fun overall, probably the best place to focus on improvement would be playtesting level design. It would benefit greatly from being able to scroll around the level easily (maybe I missed how to do that?) to plan where the shot should go; later levels have frequent long leaps of faith over water where a first time player has to waste strokes on exploration to learn where to go. There are also several levels heavily reliant on long series of unskippable moving spinners, arranged to make forward progress basically dependant on RNG. Both of these problems are often worsened by having traps nearby where it is very easy to lose progress by being pushed into an earlier part of the level - which can be fine or even a good challenge, but only if the player is in control of whether or not they hit them.