There is a similar question on the site which must not be named.
My question still has a little different spin:
It seems to me that one of the biggest selling points of Nix is basically infrastructure as code. (Of course being immutable etc. is nice by itself.)
I wonder now, how big the delta is for people like me: All my desktops/servers are based on Debian stable with heavy customization, but 100% automated via Ansible. It seems to me, that a lot of the vocal Nix user (fans) switched from a pet desktop and discover IaC via Nix, and that they are in the end raving about IaC (which Nix might or might not be a good vehicle for).
When I gave Silverblue a try, I totally loved it, but then to configure it for my needs, I basically would have needed to configure the host system, some containers and overlays to replicate my Debian setup, so for me it seemed like too much effort to arrive nearly at where I started. (And of course I can use distrobox/podman and have containerized environments on Debian w/o trouble.)
Am I missing something?


I would separate NixOS from other immutable distros. NixOS is really about giving you blank slate and letting you fully configure it.
You do that configuration using a static config language that is able to be far more idempotent than Andible. It’s also able to define packages that are well contained and don’t require dynamic linking setup by manually installing other packages.
Immutable distros, on the other hand, really have no advantage to your setup and will probably feel more restrictive. The main use I see for them is for someone new or lazy that wants to get a working system up and running quickly.