I don’t think you can compete with such mature distros, yours being so new. That being said, I’d hope you’d be welcoming to any who’d move things along in that direction. I hope that is the ultimate direction; except the one-size-fits-all attitudes of some.
Regarding a dynamic swapfile, here’s one attempt: Swapspace. The author thinks it works pretty well, and doesn’t need much updating. He says he won’t do much maintenance on it now. Maybe it could be adapted for NixOS. Here’s a discussion of how badly Linux behaves when a program uses all the memory and available swapfile space: Linux Performance: Why You Should Almost Always Add Swap Space | Hacker News. Basically, it’s almost always a hard reboot while the swapfile is grinding.
Here’s a graphic installer that functions the way I suggested, by giving you the choice of what categories of desktop software you want installed:
How to Install CentOS 8 (Step by Step with Screenshots)
I’d say, Nix says “nix”, i.e. no, to bad package managers that are subject to dependency hell, and not letting you choose what volume you can install things in. I’d hope NixOS simply ignores bad decisions of present-day linuces, and implements what it implements, right, with the eventual aim of competing with some of these big distros. I’d hope NixOS will say “No!” to bad distro ideas of the past. My (inexperienced as an OS dev) advice would be, just do it right, and hopefully others will join in.
In the present case, perhaps some of this code can be pilfered. When an author or a linux is doing something right, use it if the licenses work; or learn from it. Don’t see it as a limitation, however, if the OS of the future really should work differently. Stand on the shoulders of giants, but don’t be afraid to climb higher from there!
You could do what Red Hat does, except for the selling it part: sell support contracts, with the lion’s share of the money going to people who get paid for helping with support questions. The rest would go to a Nix foundation, which could then promote NixOS and set bounties for code development. Just trying to be helpful, to brainstorm and cheer-lead a distro that shows promise.