For macro photography, how do I choose between a compact camera or a mirrorless interchangeable-lens camera (without considering a lens)?
What indicator(s) should I look for when making the choice?
Well, you cannot completely dissociate one from the other for the compact case because the lens is attached.
As far as hardware goes all photography is primarily about the lens. And Macro photography is even more about the lens than almost any other type of general photography. You really can't choose a camera for macro photography without considering the lens. To successfully do Macro photography a camera needs to include a lens that demonstrates certain characteristics.
These are things you need to consider when looking for a camera/lens combination to do Macro photography: