Haven’t tried pairing a normal mouse and keyboard.

I wanted to use a Bluetooth keyboard and mouse because the Frame just has the one USB port, but the KDE Plasma settings don't even have a Bluetooth option. I use KDE Plasma on basically every computer, so I know where it's supposed to be. But I can connect via the Bluetooth settings in game mode.

When connected, the keyboard works fine. It operates exactly as you would expect it to on any other computer. Nothing to say about that.

But for the mouse, the pointer (the little arrow, hand, cursor, etc. that indicates where your mouse is located onscreen) seems to be bound to only the VR controllers. If you try moving the mouse, it's like the onscreen pointer is just invisible . It will activate the tooltips of page elements when you hover over them and stuff like that, and you can certainly click. But without actually seeing the pointer, a mouse is pretty useless. You can make the pointer appear by doing the "shake mouse to increase pointer size" gesture, but when you stop shaking, it disappears again.

Yeah, it absolutely answered questions I had, specifically regarding desktop mode.