If you try to pair with the PS4 controller in the usual way; enter pair mode by pressing share and the Playstation and clicking on th Wireless Controller detected in the list of detected Bluetooth devices on your switch, it will hang during the pairing proces. For me the workaround is to do a fresh reboot, pair wit a bluetooth device that asks for a pin (for me it was a Siemens SL400 dec phone) and pair the PS4 controller after that.