A: This depends on the revision. Older M260 versions (Model HSA-D005K) do not have on-board memory—settings are saved in the Windows driver. Newer revisions (T3U70AA) may have 128KB of memory. Test by setting RGB to blue, unplugging the mouse, plugging it into a different PC. If the color stays blue, you have on-board memory.
Many users assume that plugging the mouse in via USB is enough. While Windows will indeed install a generic HID (Human Interface Device) driver to make the left and right buttons work, you lose the "gaming" part of the equation. Without the official driver, your M260 is just a standard office mouse. hp gaming mouse m260 driver
A: The basic tracking and buttons work on macOS and Linux without a driver. However, the custom driver software is Windows-only. You cannot control RGB or macros on non-Windows OS. A: This depends on the revision