This is the Pokemon Sword and Shield Auto Egg Hatcher!
I saw someone post a video of something that did this for you, so I figured it would be easy enough to do it.
Found this: https://github.com/progmem/Switch-Fightstick
Which lead to this: https://github.com/shinyquagsire23/Switch-Fightstick
Which lead to this: https://github.com/bertrandom/snowball-thrower
Used the last one extensively, modified the movement set to work for hatching eggs.
How to get it to work: What you need: Arduino Uno R3, Arduino USB (Looks like a printer cable), and a Nintendo Switch
You will need to download Flip to push the payload to the Arduino
https://www.microchip.com/DevelopmentTools/ProductDetails/PartNO/FLIP
Download that, plug in your Arduino and get it into DFU mode (you connect the Ground Pin to the RESET2 pin) See here for help: https://www.circuito.io/blog/arduino-uno-pinout/
Once those pins are connected, windows should recognize that is gone, disconnect the pins
Check to see if Device Manager recognizes the device, should be under ports.
If it says Arduino still, go back and make sure you get it into DFU mode
If it says something like Unrecognized Device, right click it, click update driver.
Click Browse my Computer, Click let me pick from my computer, Click Have disk
Browse to the program folder that has Flip in it. Inside the USB folder, select atmel_usb_dfu.inf
Once you do that, it should be recognized and you are good to go!
Open flip, click select target device, pick ATmega16u2
Click Open Communication Medium, click open
Click load Hex File, select Joystick.hex and press run
In the game, fly to the daycare in the wild area.
Make sure your party is full, and the town map is in the bottom right corner of your menu
After that you should be able to plug it into the switch and watch it go!
Good Luck! If you have instructions on other platforms please let me know and I will update this!
Check Releases for the various hex files. I recently added different step counts to the releases page. Go grab whatever hex file you need and start hatching!
If you want to compile this yourself, download this: https://www.microchip.com/mplab/avr-support/avr-and-arm-toolchains-c-compilers
Add it to your path, direct yourself to the project folder and run make