Native handlers are mentioned in the post about the 54.x beta firmware and I also wrote a post (just search for native handlers).
As for groups, Hub Firmware Beta Group | Local Execution for Lighting Groups is Ready for Testing
Native handlers are mentioned in the post about the 54.x beta firmware and I also wrote a post (just search for native handlers).
As for groups, Hub Firmware Beta Group | Local Execution for Lighting Groups is Ready for Testing