Audio or visual feedback

I have a smart button that triggers an automation. The automation itself might sometimes do nothing for some time (intentionally).

I would like the user of the button to receive some feedback that the button press was acknowledged by home assistant and that the automation will do its thing in some time. Since the button itself is battery powered, I’d like this device to also be battery powered so I can place it close to the button itself.

Any ideas on what I can use for this?