Thank you for playing and for the kind words. :)
You can get past the final spikes simply by double jumping over them, it is enough to not take any damage. Or, if you are up to a challenge, you can try to scale the wall (which also takes some double jumps, but it takes some skill to time them properly) and then jump off of it when up high. The bosses were the last thing I did and I did not have enough time to polish them properly, so some of them turned out to be cheesable.
I did not know about the Gameboy Jam, so thank you for letting me know it exists. :)