Here's the easy way: Read the NixOS thesis. If after reading it you're not compelled to use NixOS, then NixOS is not for you.

There's no denying that there's a steep learning curve to Nix and NixOS. But that doesn't matter if you've become convinced that what NixOS has to offer far outweights the effort you'll need to put into learning it.

BTW, the Nix package manager can't replace the native package manager (ex. dnf). You'll see what I mean after you read the document linked above.