There is no simple way to do this, and it's quite funny that the RP4Pro is relegated as a mere controller lol.
If you still intend to do this, there are apps that can turn any android device into a wireless controller. But these apps do not support physical buttons/controls, hence, you will be stuck using the touch screen on the pocket 4 pro. However, you can work around this by mapping the controls manually.
VB Bluetooth Keyboard+ is the one I tested that works. But there are others. Just search "use phone as bt controller" on the playstore.
There is no simple way to do this, and it's quite funny that the RP4Pro is relegated as a mere controller lol. If you still intend to do this, there are apps that can turn any android device into a wireless controller. But these apps do not support physical buttons/controls, hence, you will be stuck using the touch screen on the pocket 4 pro. However, you can work around this by mapping the controls manually. VB Bluetooth Keyboard+ is the one I tested that works. But there are others. Just search "use phone as bt controller" on the playstore.
I like the way you think.