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sudo in Windows.Please report posts and comments that break these rules!
Important: never execute code or follow advice that you don't understand or can't verify, especially here. The word of the day is credibility. This is a meme community -- even the most helpful comments might just be shitposts that can damage your system. Be aware, be smart, don't fork-bomb your computer.
It's not about the destination, it's about the journey.
I am a Gentoo user and most of that is already a reality on Gentoo systems. Get the stage3 tarball set up, slap your /etc/portage/make.conf and /var/lib/portage/world files in there and build.
Obviously, depending on whether it should be a blank system with the same apps installed or a clone of a previous system, configuration in /etc and one's home directory may need to be copied, too.
With gentoo and arch you are learning how linux works. Replace nixos with salt or ansible and it can even get you a job.
NixOS is still a Linux system, and the configuration still translates to stuff you have in a very similar way on every other Linux system too (with the exception of what's needed for the file system layout to work). It's not some kind of magic. I've probably learned as much stuff applicable to general Linux distributions as while using Arch and Gentoo.
Of course, if you only use the high-level options and the graphical installer that may be different, but then comparing it to those distros is very disingenuous.