Poor component experience

I just can not add a new component to a variant of a component set. Why if Adobe Xd just simply allows to stack a full component interaction and variants

It works fine here, if I understand you correctly. Just drag an instance of a component in one of the variants of another component.

Here I have an accordion that has another component for the content. That content component also has variants so I can switch between different content types.

The accordion Group has 2 variants: “open” and “closed”.