Not possible to ADD SCENE at all - Video Editor No options to add a scene, at all.  Either a new one or existent.
I have tried with either complex animation and the default cube scene with one keyframe of displacement.  In both cases the same message &quot;No items available&quot; for creating a new scene.
I have rendered the full animation and it only allows me to insert movie strips and audio.
Version 2.90
First of all, make different scenes, each one with their animation.
Then make a new scene without any animation and open the Video Editing tab.
Finally, from the Video Editing tab, try to add a scene either by Shift+A with the mouse hovering on the Video Sequencer panel, or as you did, by clicking on the Add&gt;Scene dropdown menu.
You should be able to find all scenes but the new one you're video editing from!