Custom Randomized Mouse Mover

I need a plug-and-play USB dongle that quietly presents itself to the laptop as a standard HID mouse and then, without any host software, begins moving the pointer in truly random, human-like paths. Every travel should land on random points across the screen, never following a predictable grid or loop, and the velocity needs to ebb and flow so it looks as if an actual hand is guiding it rather than a script—variable speeds are essential.

Because I will sometimes want to pause the motion or cycle through a couple of intensity presets, all adjustment must live on the device itself: a small tactile button (or a pair, if easier) that toggles the mover on/off and steps through, say, slow, medium, or fast randomness. No companion app, driver, or registry edits—just pure hardware control.

I’m happy with any microcontroller that can enumerate as a USB HID device (ATmega32u4, RP2040, STM32, etc.) as long as you supply:
• A fully assembled, tested dongle ready to ship
• The firmware source and brief build instructions so I can re-flash if needed
• A short user sheet showing what each button press does and the range of movement speeds

The end goal is a discreet, reliable gadget I can trust to keep my machine awake while passing even the keenest “is someone there?” eye test.