Ansible is a different tool than Nix. It's been specifically designed to fit your exact use case. If ansible works for you and your team, there's no reason to drop it.
I've never had a moment using nix where I've felt "wow I couldn't do this with any other tool". That's not really the benefit of nix. The benefit is the flexibility of the idea and the tooling.
It's a flexible enough platform where I can use one config to manage 5+ computers in my house with various operating systems. I can use it to easily setup all my dependencies for my work projects. I can use it to build my work projects. I can use it to create vms to test those projects on. I can use it to build 3rd party projects without any instruction.
All that required was a few months of pain learning the fundamentals of nix and I've received the rest for free pretty much. It's the epitome of upfront work for long lasting benefit in my opinion.
I've never had a moment using nix where I've felt "wow I couldn't do this with any other tool". That's not really the benefit of nix. The benefit is the flexibility of the idea and the tooling.
It's a flexible enough platform where I can use one config to manage 5+ computers in my house with various operating systems. I can use it to easily setup all my dependencies for my work projects. I can use it to build my work projects. I can use it to create vms to test those projects on. I can use it to build 3rd party projects without any instruction.
All that required was a few months of pain learning the fundamentals of nix and I've received the rest for free pretty much. It's the epitome of upfront work for long lasting benefit in my opinion.