There is a plugin for almost all platforms (web, iOS etc) which is allowing to animate vector format images (you animate it in After effects and export json for devs, then devs with few commands can play/pause on that json).
Would be nice to implement support of Lottie into Principle with ability to play/pause and animate with drivers.
For example Onboarding images have morph-transition pre-made json animation when you horizontal scroll-pages of it. Like here: Animated Onboarding Experience by Divan Raj on Dribbble.
If implementing Lottie is hard, then maybe controlling video play with drivers is something what can help too (since we can export video mp4 for prototype, and give json to devs).