Creating RHEL9 Images from a RHEL8 ImageBuilder?

I'm having trouble finding a statement about OS version capabilities for imagebuilder.

With image builder on RHEL8 I can't see any RHEL9 possibilities. Is this correct or am I just missing a step to support it?

If I need to go to RHEL9 on the image builder server to produce rhel9 images, can the rhel9 imagebuilder then produce rhel8 images as well? Or do I need a separate instance per supported OS?