I wanted up add Klipper to my Ender 3 V2 Neo but all I had was Raspberry PI 4 8GB units, bit of a over kill. I came across some one that has shipping Raspberry PI Zero 2W in stock: Canakit, $15 each and runs Klipper without issues. The old Raspberry PI Zero W has issues with Klipper.
Recommend models for Klipper are Raspberry Pi 2, Raspberry Pi 3, or Raspberry Pi 4, the Zero and Pi 1 models dont really have the processing power to keep up and remain stable. Havent seen much mention of the Zero 2 boards as most people tend to go for the full blown pi’s for reliability and stability.
Raspberry PI Zero 2W is a PI 3 at 1Ghz, both the PI 1 and 2 do not have Wifi with 900Mhz and 700Mhz clocks.
The PI Zero and PI Zero W are single core very low power devices and while they can run linux they do it slowly… The Raspberry PI Zero 2W is being used without issues on Klipper, google is your friend, and 2W uses way less power than the PI 4. It only has 512MB of memory but you can use a 64GB SD card for all the jobs and logs.