The Steam Deck is a very flexible device and one of the things that you can do with it is install Windows onto it.
Now, I'm going to get right into the meat of the article and give my pros and cons behind having Windows installed on the Steam Deck.
Flexibility is one of the main pros for me, when Windows is installed on the system it allows a lot of freedom. You can download and install other game launchers such as Ubisoft Connect, BattleNet, Epic Games etc. I liked this, because of the free games which I've picked up over on Epic Games store. However, there is a way to download these games through desktop mode on SteamOS using Lutris or Heroic Games Launcher, but I have to admit, I haven't had much joy with getting games launching or working smoothly using this method.
Having Windows installed also allows you to play games which might not be possible through SteamOS due to Anti Cheat not being compatible with Linux, so games like Destiny 2, Modern Warfare 2, FIFA 23, are all playable on Steam Deck when Windows is installed.