And also, are you too lazy to update your system occasionally, which is a simple command or a few clicks? Because how is needing to click a few buttons every few weeks/months "bad UX"?

It's not the point whether they do. the average people wouldn't. that's why it needs to be automatic, or why the easiest way should also do that.

And also, are you too lazy to update your system occasionally, which is a simple command or a few clicks?

No, as said. This is about recommending distros for people switching from Windows. Not my personal hobby machine.

click a few buttons every few weeks/months

That is too rare. You should update at least weekly.

And yes it is silly

1. "You have an update"
2. Open a graphical appstore for no reason
3. Show you a bunch of packages, unless you are an expert you will not need that info and click "yes" all the time
4. Wait, with an open GUI window
5. Often you will be prompted to reboot

Why? Updates dont need a GUI and can go fine in the background. An update notification to reboot once done works too.

And NixOS as well as Ostree or bootc based distros offer you multiple boot targets, so if something breaks you can go back.

OpenSUSE Tumbleweed/Slowroll are my go-to if I want something more messy (if I want to do changes to the system without caring about packaging), as they have snapshots by default.

whatever atomic distro you mention has a small repo

No idea what you mean. If you search for "universal blue", "bluefin", "aurora", "fedora kinoite" or "HeliumOS" you will absolutely find it.

NixOS, which i doubt since you need to reboot to update

Nixos supports fully atomic updates which should be used. The live updates always break stuff.

I am on NixOS, but for beginners I would recommend uBlue or CentOS-Stream based atomic desktops. Fedoras biggest issue is that they have no longterm kernel