i suppose this is a one-off project for you or are you creating a device for distribution? if you are creating the latter, how did you clone this to other devices, i'm assuming dd?

I'll probably prep the "gold master" SD card and then leave it to our SD duplicator.

I'm aiming to distribute SD cards that make some of our Pi Zero kits - Radio, Mood Light, etc - near frictionless to get up and running.

I found the use of Qemu + multistrap in this tooling easy to get my head around and I additionally wanted a stateless RAM disk so customers couldn't fubar it.

I didn't have much luck with Buildroot.

I evaluated TinyCore/PiCors too and I love the concept, but it's just a little contrived to ship to beginners. The way it mounts whole packages of overlays/dependencies is clever though- I am doing something similar (inspired by Open Pandora's pnd format) to add a custom build of VLC to PiratePython for our radio kit. Package the whole app + dependencies into a container image, drop it onto the SD card, mount and simlink everything into place.