You could totally use HID Remapper to do what you want.
The PlayStation Access Controller has profiles that can be configured from a PS5 as you say, but regardless of the current profile or mapping, it always sends the raw button/joystick states in the report. They're not properly exposed in the report descriptor, but they're there. You would have to use what HID Remapper calls "custom usages" to get to this raw data. I can assist you with that if you're interested. Though it might be easier to find someone with a PS5 for the one time setup.
It does use a 3D compass (magnetometer), but it still needs to be told which direction is "up" as that depends on your orientation with regard to the screen.
There is no PC part. It is a standard Bluetooth mouse and works with any computer, tablet or phone with no additional software, as long as it supports the standard protocol.
It doesn't know so the initial orientation is arbitrary. You have to set the "up" direction by touching the ball with a magnet in the right spot (there's a reed switch inside) and rotating it around the Z (vertical) axis until the directions are correct.