Hi @Nicolapps,

I finally managed to have a working implementation for the clustering. The solution is not perfect, but it I tried many things and this ended to be the most reliant and easy to maintain solution. Technically what it does is return an empty cluster annotation and implementing a new Annotation with the cluster coordinates. I implemented a hook to get the coordinates so it should be easy to implement it by the user. That way we can reuse our Annotation component and do not have to do a complete re-implementation as the annotationForCluster function expects to be returned the MapKit Annotation and not a DOM element and we do not need to do a complete re-implementation of our Annotation and Marker component where we would need to return the component instead of attaching it to the map while also handling the createPortal stuff for the React part.

Let me know what you think about it, I would be happy about a review and can also do some cleanup of the code and example if this is the variant we are agreeing on!

fixes #61

Edit: There is still a major issue in unmounting the cluster annotations unfortunately, not sure if it is possible to fix with the current implementation or if I need to go for another variant. I cannot mark the PR as draft.