The way the dependencies are copied into
vendor in Core is unideal, but is a bit of legacy from the early days of the product. Due to prioritization/limited resources, this is unlikely something that we'll get to refactoring soon (i.e. not within the next 3-6 months) — however, since Animator Core is fully open source, it should be straight-forward for anyone to fork and make some nominal modifications to make it a bit more sane & tree-shakable. We would welcome PRs back to the main project, too.
Another option for reducing footprint is to check out using
lottie-web as your web runtime, as long as you don't need interactivity or framework adapters.