I feel similarly. It seems to have a lot of good things going for it.
When I first investigated it like a decade ago, one majorly offputting aspect about it is that I didn't see it as offering the capability to install multiple copies of things. I greatly prefer systems where i can blue-green deploy services locally, or otherwise have special purpose instances, and Nix, at the time, didn't seem to have much interest in that. I believe things have changed a lot in that regard, or perhaps my couple hours spent as an utter neophyte poking around for answers didn't surface the clues.
I would say that, these days, I am far less interested in configuring a system. I am far less interested in the desktop. To me, my time is 100% not worth investing in these goals. I am trying to focus on working with & orchestrating a fleet of machines, in a coordinated fashion. I believe free-software folks should all be re-investing, re-focusing similarly, in running & operating personal/manorial/federalized "cloud" systems. I happen to agree with a lot of the philosophy of Kubernetes- a desired state management system for resources, and controller/operators that autonomically enact & maintain that state- and invest my time & work trying to make it an useful fabric for my & hopefully my friends digital homes.
...just, well, not quite enough that I want to spend time learning how to use it. :/