Pico remotes are "Button Controllers", which do not persist any state. This differs from a Switch or Dimmer devices, which has state values such a "switch: on or off" and "level: 0-100".
Since the Mirror apps simply mirrors that status of one device to another device, it cannot be used with a Button Controller device.
I personally use the Advanced Button Controller (ABC) community app with all of my Pico remotes. It works great and is easy to configure and use to control a variety of devices.
