I think NixOS is awesome, but it certainly doesn’t offer “access to (basically) all Linux-capable software, no matter from what repo.” - at least not natively. You can do that through containers, but you can do that with containers on any distro. Where it shines is declaring the complete system configuration (including installed programs and their configuration) in its config file (on file-based configuration, I wouldn’t really consider blendos a viable competitor).