From the product details it looks as if there are pins on the UPS board which connect with the underside of the RPi.
May I ask why you want a UPS? If the power goes off, presumably all the devices controlled by HA will go down - giving a whole mess of errors if HA is stil running.
It’s mainly for the alarm as the motion sensors are all battery powered and the siren has a battery backup inbuilt.
Just bought an argon one case so doesn’t look like this would fit anyway now.
Any decent options for an argon one case or should I just get a powerbank with pass through charging?
Also is there any way to setup this so that if power goes down for the internet router it then uses a SIM card dongle as a backup?