Whatever linux version is on the Steam Deck wasn't bad to use when I needed Desktop mode. It was pretty similar experience-wise to windows (no mac experience).
SteamOS is based on Arch, which you do not want to use and maintain as a beginner. what matter is the desktop environment, which in SteamOS' case is KDE Plasma, a great choice in my completely unbiased opinion.
Good points.
Its worth mentioning that while SteamOS is based on arch (a famously unstable distro), it is immutable, so the user will have a much harder time bricking their system.
KDE plasma was the right choice I agree, considering the number of windows users Valve is marketing towards.
That's probably KDE - the K Desktop Environment. Linux variants are called "distributions" and they are basically software bundles maintained by groups.
Desktop environments are basically bundled themes and software to present a desktop, bars, effects, and so on. Windows basically has one desktop environment, but linux has many: Most popular are KDE (windows like) and Gnome (Mac like), but there are more like Cinnamon, XFCE, LXQt, LXDE, which look more like windows.
Desktop environments also have window managers - they do what they say, manage your windows: maximize and minimize them, stack them (stacking window managers), tile them (tiling window managers), or even allow only one window at a time (like kiosks).
If you want to start your linux journey, grab bazzite if you want to game or linux mint debian edition (comes standard with cinnamon desktop environment, but you have the choice during installation to use KDE too) and give it a go!
You can also test distros (linux mint for example) online!
Or better yet try it on your main notebook/desktop. Try to get the same things done you did before with Windows and if it works for you, stick with it.
yeah, Id recommend switching on your secondary machine, so you can try it out and use it properly, but not get frustrated if it does something you don't expect.
I tried the odd distro here and there over the years on my old laptop/"secondary" device or whatever you want to call it, and while you get some experience with the different desktop environments and whatnot, I can't fully replicate what I'm doing with my main computer on my older laptop. Gaming is a big thing for me for example, and my laptop has an old GeForce MX250 which doesn't cut it for today's games.
What I ended up doing to really give desktop Linux a try was installing it onto a separate SSD on my main machine. You don't need a separate SSD of course, you could just repartition your existing one and install a Linux distro side by side with your existing Windows installation.
And then I just used my computer (or attempted to) for whatever I would've done on Windows at that time. So if I wanted to play a game, I tried installing it (via Steam or Bottles for example) and checked whether it worked. Same with voice chat, screen sharing, development stuff, photo editing, media consumption etc. The few times I booted up Windows again was to update the firmware of a game controller and to transfer save games I hadn't backed up elsewhere (my Windows partition is BitLocker encrypted and while you can certainly mount it under Linux, I didn't feel like it, rebooting was much quicker).
Sure, using an old device can work for checking out some things, but at least for me I wasn't sure at all until I tried doing stuff on Linux that I also did on Windows. YMMV.
If you have actual work to do then I would HIGHLY suggest not doing it on your main machine. Give it a month on a secondary machine before giving up. If you install it on a Friday night and come Sunday night it's still not working fully you're gonna go back to Windows and never go back.