To clarify, I was referring specifically to its ability to specify the full system configuration in its config file - not overall. But I haven’t used blendos, and my impression is mostly from a quick look at their documentation. They have a snippet with sample configuration. There, they have a “Modules” section, but I couldn’t find what modules are available, what options they have, how to configure them if we want to do something more complex than the available options.
Then containers are clearer: they have a list of installed apps, and then commands to bring them to the desired state (somewhat similar to a dockerfile). But even then, i imagine that if you have a more complex configuration, that’s going to get clunkier.