I was able to test it now and managed to connect the keyboard as well as the mouse from the Pop series to the Xbox. The procedure was relatively simple. First I connected the keyboard and mouse to the supplied dongle using a laptop. The dongle saves the connection. Then I just had to connect the dongle to the Xbox Series X and it was recognised.

As far as I know not, because the two devices have different Bluetooth, one is from Microsoft and the other from Logitech. Please don't hold me to this