You can also make your own USB drive mini-distro, atop Debian.
With LilDeb, I made a layer atop Debian Live, including an optional mutable partition, and curated a package mix and configs for it: https://www.neilvandyke.org/lildeb/
As the very top of the page says, I'm not maintaining it, and I preserved it online. It's an example of a way to make your own distro. Considerable work went into the `build-lildeb` script that is a single file to define the distro in a simple and lightweight way. (This was before Dockerfiles, so maybe newer then, but it's still practical.)
A current implementation of the same abilities is probably the source used to spin SpiralLinux. I haven't tried this myself but it at least looks possible.
With LilDeb, I made a layer atop Debian Live, including an optional mutable partition, and curated a package mix and configs for it: https://www.neilvandyke.org/lildeb/