Custom stages for preview and custom tooling (PreviewSceneStage, StageUtility...)

Hello !

I stumbled upon the following blog post, regarding the implementation of custom "preview stages" :
https://samuelarminana.com/index.php/2020/09/28/unity-editors-stages-and-scenes/

The guy leverages some Unity API I never heard about like StageUtility, PreviewSceneStage...
It looks like these APIs are used in particular by the Prefab preview context.

Is there some documentation/workflow to be used for the end-users ?
Could we implement custom preview context, or is it a danger zone for end-users ?

Thanks !

EDIT : found an older thread about it (https://forum.unity.com/threads/what-is-previewscenestage.762734/#post-6346353)