Debian SBuild for FreeBSD People

For other-$WORK I am doing a bit of Debian packaging (prep-work) and upstream wrangling to bring some projects into a more-modern world. So now I have a Debian 13 workstation and need to build things for Debian Unstable without breaking my host system. On FreeBSD, this is a job for Poudriere. Here’s my notes on how I do something half-assedly similar on Debian (as usual, mostly documentation for…