You can read the full post on the VRChat dev blog here from August 30th 2022:
VRChat, the virtual reality social platform, has announced the release of its Creator Companion tool, version 1.0. The tool, which has been in Open Beta since the “Creator Toolbox Update” announcement three months ago, is now available for general use.
Purpose: The VRChat Creator Companion (VCC) is designed to make creating content for VRChat easier. It helps users set up their computer for content creation, including downloading the Unity Hub, the required version of the Unity Editor, and the SDKs. Additionally, it allows for the creation of new projects quickly from its built-in template for Avatars, Worlds, and UdonSharp projects and updates projects by migrating them from the old package format to the new one and installing new versions of the SDK and community packages.
Changes to Packages: The VRChat Package Manager (VPM) is a library used by the VCC to handle the new package format. This format is compatible with the Unity Package Manager and uses the “Packages” folder of the project instead of “Assets”. This makes it much easier and cleaner to change and update packages as they always perform a “clean install” without the need to delete anything in the project. Additionally, packages can declare dependencies on other packages, which can have their own dependencies, and so on. The VPM can manage all of this and automatically get everything you need to use a package.
Compatibility: Many existing prefabs and packages will continue to work without changes while others will require updates. If you’re a prefab or package creator, you can read the docs on Converting Assets to a VPM Package to learn about the process or try out the Package Maker tool which automates much of the process. If you find something that doesn’t work with the new system, you can reach out to the original creator and ask them to upgrade their packages.