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?
Your summary of the language is spot on. I still hope that more distros take inspiration from the declarative config and try to move in the direction, or nix supports a better language in the future. I think that ultimately that’s what the average linux user would want. The ability to still customize in a safe manner. Silverblue, and others, are and will remain a great option for the new or indifferent user.
On your point about the transient phase, nix actually does that by default already. It installs everything at a separate path and then flips over in one go. You can even pick the mode, either try to do a live switch as you describe, or on boot. I don’t know if I see many benefits to images there.
I am at a second place now that uses NixOS in a corporate setting, and it is much easier than maintaining the CoreOS images, or similar. I’ve had some many broken builds of CoreOS images because something goes wrong between the custom packages and the base CoreOS images, I would rather just run an Ansible script at this point. Also, you end up using the exact same test suite for NixOS images as for your other images, so the same guarantees end up being met.