I don't know if this will be of any help to you as I am trying to fix a problem of my own (I can't get the Reshade control panel to load when I'm using Vulkan)
But, you referring to Default = Fn+F2 caught my attention as I thought the default key binding was the HOME key.
I quickly tried your shortcut combo which didn't work for me. Actually, on my Win 10 system, pressing Fn+F2 loads a small popup window displaying the current volume setting.
Pressing Fn+F2 repeatedly increases volume and Fn+F1 decreases it.