That is very cool. Thanks for sharing. If you need some additional repos (like OP), you can probably add them through some commands in the "pre_init_hooks" option.
It should be possible. Although probably very complicated. Have a look at https://distrobox.it/. It allows you to tightly integrate containers into your desktop, including accelerated graphics, some devices, your homedir, etc. It can even automatically install desktop shortcuts. (You can disable the integrations of course)
Even tho it uses Podman instead of docker, AFAIK it should be 1:1 compatible with docker for your usecase.
Mine was Windows XP -> Ubuntu -> Xubuntu -> Windows 10 -> Kubuntu -> KDE Neon -> back to Kubuntu -> Manjaro -> Endeavour OS -> Fedora -> Debian -> NixOS
I also have a separate Laptop for financial things running Alma Linux and a Gaming PC running bazzite
The guy posted cross posted it to c/OpenSource, so I guess