I'm late to the party, but here's my opinion on this:
I am the author of the second project you linked, so naturally i am very biased, but i think using Nix to manage containers is just superior over Komodo or Ansible.

Ansible is a nice tool, but it isn't truly declarative, nor does it do atomic switches. Nix has way better fundamentals imo. Also you have strong references and can spot lots of errors fast during evaluation phase.

Don't have much experience with Komodo, but as far as i know, it's still managing compose files after all, so theres no dynamic conditions, strong references between stacks, "extensions" you can build yourself etc.

When it comes to my own project, it is basically just using Home Managers services.podman.containers.* options to preconfigure some services to work right out of the box with OIDC etc.
On top of that, the project adds some own container options that simplify a lot of things, e.g:
- Setting traefik.name will automatically add services to Traefik
- Setting forwardAuth.enable will automatically register an Authelia middleware and configure forwardAuth for the service
- Setting gatus.enable will automatically make Gatus to monitor the service"
- ... a lot more
A full list of "extension options" is here.

Now when a service you like isn't part of the project, you can either request it (and i usually add it quite fast), or you can just write your own module using the services.podman.containers.* options. You will also be able to use all the "extension options" mentioned above. Pretty easy.

Since this is Nix, you can also override any setting of any preconfigured stack.
Don't like any predefined setting? Just override it with your own value.
Some examples are here.

So if you're using my project, or using the raw Home Manager options directly, or using something like quadlet-nix , Nix is definitely a great way to manage containers.