ungoogled-software/ungoogled-chromium-debian ? reverse-engineered prompt

Build me the packaging project for ungoogled chromium so I can make Debian and Ubuntu .deb packages from the git repo.

I want a clean unified setup that works for the supported releases, especially Debian Sid, Ubuntu Jammy, and Ubuntu Lunar, and it should be able to build on a normal x86 64 machine. Please make sure the build flow is straightforward, with the source prep, dependency install, and package build steps all working end to end from the repository. If there are any missing details from upstream Chromium or the packaging docs, look up the current docs online and wire things up the practical way.

The goal is that someone can clone the repo, initialize what they need, install the build dependencies, and produce a binary package without having to figure out all the packaging pieces by hand. If there are any small helper scripts or config files needed to make that happen, add them too.