Hello,
As of yesterday, Viewer API 2.0 is now available in the stable channel from version 2.18.1. 
For those using the viewer in their applications and concerned about compatibility, we have good news! API 2.0 includes a built-in legacy implementation that emulates the old API precisely. By using the LegacyViewer, you can benefit from API 2.0’s numerous enhancements with minimal changes to your existing code. A quick migration guide will be available shortly.
We’re finalising the comprehensive documentation, which will be released soon.
We welcome any feedback you may have.
Cheers,