Slightly tangential but I never ended up switching to nix (or guix) precisely because I don't fully understand the theory behind why things were done the way they were done and where the security boundaries are supposed to lie relative to a "regular" distro. I found plenty of prescriptive documentation giving me recipes to do anything I might be interested in doing but not much in the way of design documents explaining the system itself.

I never asked around so maybe that's on me. Debian works just fine though and containers are (usually) simple enough for me to wrap my head around.

I didn't end up using Flatpak for the same reason.