Hi all, I'm the author of the Blender addon mentioned above.
I've also been working on a proper animation program for Lottie, I just released a first version of it: https://gitlab.com/mattia.basaglia/glaxnimate/-/releases/0.1.0
(It's free and open source)

Since it's the first release it doesn't have all the features that Lottie supports but I have to start from somewhere :P It should be more than enough to create simple animations.