The downside of NixOS is bad documentation. Which makes it take quite a while to get your config setup the way you want. Its so worth it though. I used arch for 5+ years and have been on NixOS for about 6 weeks now. I’m definitely never going back. My conifg is done, I barely have to change anything now. Its all saved in a git repo so I never have to make it again. I’ve already switched all of my machines over. And even a few of my friends. Which has been super easy to do cause I just give them my config then remove everything they don’t need. I’ve only been using it for a little while but it feels so reliable and Unbreakable even though I’m running unstable packages. Because if anything breaks you just go back to the last generation that worked. Which made me willing to just try anything when I was setting it up.
Also you could run Nix package manager on arch for this, but the nix package repo is amazing. It has everything i’ve needed or even thought about installing. And in my opinion its way better than using AUR packages. Most of the time you just DL them and don’t have to build them. Its just so much faster and more reliable then using Paru or Yay. Plus there is a NUR( nix user repo) but tbh I’ve never even looked at it.
The other con I know of is issues running binaries and app images. But there are was work arounds for them. I use a few app-images by just running ‘appimage-run <appimage filename>’. And so far its worked perfectly. As for a binaries you can use steam-run or I think using distrobox would work. But I haven’t had to do anything like that yet.
I found this YouTube channel quite useful when I was setting mine up. Vimjoyer