I learned a bit about publishing a browser game on itch - never put it in fixed 1920x1080 ;) Also implemented Leaderboards which turned out to be pretty straightforward. I also validated that my ideas work - got a lot of positive comments on my game. Finally, I saw that I can make the player feel certain emotions thanks to proper design, which was also reflected in the feedback.
Overall, even though I was quite late to the party I'm glad I joined this as my first Game Jam!