Those devlog updates are always a highlight for me, thank you so much for so many detailed insights!
Your paragraph about the hassle of trial and error when iterating on animations inspired me to work on a tool during our last company hackathon: With Playdate AntiMirror you can at least stream and review in real-time your desktop content on the Playdate. It's not quite the animation engine you were describing (I am thinking if "Rive for Playdate"), but I hope this is of some value for you!