HID VS HoodLoader2

I don't think the built-in keyboard library identifies itself as "boot capable" in the HID descriptor, which is necessary for simpler keyboard devices. Try using NicoHood's HID library with the "BootKeyboard" object.

Looks great! How did you handle the programming? Did you follow a guide, or did you implement the Arduino HID Project library?

Skip the esp then and pick up any dev board supported by the HID project.

You can make it act like a HID - which is what I assume many people have done - with custom drivers like this one. https://github.com/NicoHood/HID

You can use Arduino HID Project which allows to reprogram atmega16u2 which performs USB communications on Uno. Then you can upload HID sketch on 16u2 and "normal" code on atmega328 which would do everything and send desired wheel state via serial. On 16u2 side you will parse that serial command from 328 and translate it into HID message

I'm trying to grab the "microphone muted" LED status from the HID library, but it seems like the library only supports a select few statuses out of the box: https://github.com/NicoHood/HID/issues/151

https://github.com/NicoHood/HID for a real UNO

Nano (atmega328) doesnt have native USB support (just a USB to UART converter). UNO also doesnt have native USB support, but has a atmega16U2 on board. You can flash this chip and build a USB HID bridge -> https://github.com/NicoHood/HID/

Try using NicoHood's HID project and the system key page: https://github.com/NicoHood/HID/blob/master/examples/System/System.ino

The Mega2560 like the Uno has a second MCU that does the USB-Serial stuff, an atmega16u2. You can flash this one to show up as a USB HID device instead of serial through Hoodloader (https://github.com/NicoHood/HoodLoader2).

The library is compatible with all boards using the MCU ATmega32U4. This includes Arduino Leonardo, SparkFun Pro Micro, Arduino Micro, and Adafruit 32u4 AVR Boards. It also supports the Arduino Uno and Arduino Mega, but this requires the HoodLoader2 bootloader, see this wiki for more details.

hoodLoader2 might help you out. I've no experience with it though.

You should buy a Leonardo if you want to do USB projects, the Uno can do that stuff too - it has a small microcontroller (16u2) that's a cut down version of the one on the Leo (32u4) that handles the USB to serial conversion required for a PC to communicate with the main microcontroller (328P) on an Uno, the 16u2 can be reprogrammed to make the board appear to be anything - but it's harder to achieve for beginners. If you're interested in reading more, take a look at https://github.com/NicoHood/HoodLoader2, but if you just want to do keyboard and mouse stuff quickly with all "off the shelf" hardware and software (and the community support that entails) the Leo is definitely your best bet.