It is currently not possible.
It's theoretically possible, but it would be an incredible burden to maintain and make polished. Lottie doesn't quite have a spec and often introduces breaking changes. The Lottie format came from reverse-engineering the After Effects file format.
Our exporter is built by reverse-engineering Lottie's undocumented format and transpiling Animator Core's code format to Lottie's JSON.
So in short, we've filed this as a possible future feature — one which would unlock proper After Effects importing! — but it's not currently near the top of our backlog.