I really like the declarative paradigm of NixOS, but the way I use my computer often actively go against this paradigm. Next I found out about atomic distributions such as Fedora Kinoite and Aurora, and I really liked those too except for the fact that I had to layer so many packages which sort of defeated the purpose of using their images (not everything can or should be run in distrobox containers). This past day I've been setting up a custom image using the ublue-os image template and I'm surprised by how easy it was to get going. The only negative part is having to use GitHub, which I would prefer to avoid.
I just wanted to make this post to highlight how easy it is to customize atomic distributions (assuming you want to use atomic distributions in the first place, traditional distributions are of course easier to customize). If you have any questions, feel free to ask!
FWIW, there's also BlueBuild and it's used by projects like secureblue for setting up their custom images.