Hello dave_715,
Thanks for posting. I understand you have a question about controlling the volume of your AirPods Pro when using a non-Apple device.
It sounds like you're able to adjust the volume as expected when paired with an iOS device. In order to adjust the volume on a non-Apple device, you would need to use the device's controls. This resource has a little detail that might explain: Connect and use your AirPods and AirPods Pro
"To change the volume, say "Hey, Siri," then say something like "Turn down the volume." Or drag the volume slider in the app you're listening to, on the Lock screen, or in Control Center. You can also open Now Playing on your Apple Watch and turn the Digital Crown to adjust volume."
Since you wouldn't be able to control the volume using "Hey Siri" with a non-Apple device, checking for a volume slider as described above would be your best bet.
Take care.