I've noticed when I create a Group of switches, and then try to access that Group within Configure Scene, it only appears in the Select Bulbs dropdown box, not the Select Switches dropdown box.
Yes, it all depends on how the device lists are built, so in the group app we decided to prevent the same device from showing up in multiple lists, this prevents the posibility of the device being selected more than once, but this isn't the normal pattern for device selectors.
I plan to have several multi-tap (scene and notification) switches where it would be nice to select the same action for the same trigger event across those buttons.
You can do that with Rule Machine. Select āButton deviceā as the Trigger Event, then select the button devices that you want to have share the same actions. This assumes that those devices present the button capabilities.