Super interesting! Thank you for this. I was working on a hardware project that this probably would have helped a lot with. I was writing some python but the package couldn't be compiled on my local machine so I had to run a dev server off my pi directly. I wonder if this can help.
I had the same need and also cobbled something together to do it. This project looks far easier to use, so I will also likely switch.
Checking the Dockerfile this also uses qemu to run the actual ARM binaries, I really liked how easy it was to set this up back then. All I had to do was loop mount the RPi image and then chroot into it. Everything else was handled transparently by qemu. Of course, I didn't have nice things like resize, so I was limited to making small additions.
This is exactly what I was trying to do a few months ago, but all the RPi VMs I found were a pain in the ass and I never got it to work. Ansible deployments are conveniently but take forever on RPi, golden images are great for distribution but suck to make. Using Ansible to deploy to a VM and then exporting that image for flashing is the best of both approaches.
