heneault/yocto-pitrezor ? reverse-engineered prompt

Build me a small Linux image for a Raspberry Pi Zero or Pi 4 that boots straight into the pitrezor wallet software when it powers on.

I want the whole thing to be easy to build from Docker, with one script I can run locally to produce a ready to flash image zip in the build folder. Please make the default target work for the Pi Zero, but let me choose the Pi 4 option too if I want it. If there are any setup details or current build instructions that have changed, check the latest docs online and make the process as simple as possible.

The end result should feel like a complete appliance, not a general purpose Linux install. It should start the wallet software automatically at boot and be packaged in a way that I can move onto an SD card and use right away.