The simple answer to these questions is no, the dimmer can't be used as a remote, nor can it be decoupled.
The rotary dimmer must always have a light circuit connected to it, so there is no way to control another device separately from the light circuit. However, you can use your smart hub to set up another device to mirror the dimmer.
To control another device, we also sell remotes that can be mounted to the wall.
Our modmotes can be found here: https://candeo.io/store/zigbee-smart-wall-switch-remote/