The steam deck is idiot proof out of the box. Without knowing how to unlock it, you literally cannot fuck it up and it's plug and play by default. It won't even show you games that haven't been explicitly whitelisted to be verified as fully playable. You have to go into an additional menu to check "allow steam proton to run on any game" to get the full, unlocked library of steam open to you, and even then you still can't fuck it up from there. To actually fuck things up, you have to go to desktop mode, which is just plane jane normal linux, and even there, if you fuck things up, the way the steam deck handles updates and fuck ups is that valve updates are actually just entire images of the entire linux rootfs in read only mode that overlays ontop of the normal install. Meaning, unless you actually know what you're doing to do so in linux, your permissions on the file system are completely locked down so you don't trip over your own dick. The only folder you have write permission to is your home folder, which you can't do anything other than download shit to from firefox. And if you DO somehow fuck it all up, all you have to do is hold the volume button when powering the thing on, and it goes into recovery mode, which is simply it reflashing a pre-made image onto your rootfs from an embedded ROM (or USB drive if you want). When you actually interact with the steam deck outside of unlocking it, it looks exactly like a console, with big "INSTALL" buttons on the games you want to run:
There is no way to accidentally fuck things up, if you want to fuck up your steam deck, you have to explicitly go into desktop mode and fuck around with a lot of non-intuitive console commands from a terminal. There are no buttons you can press that will fuck things up for you, it's impossible to screw it up unless you actually know what you're doing.
To "set up" your steam deck for playing on a TV, you just buy a dock, set the steam deck on it, and plug an HDMI or display port cable into the dock and the other end to your TV. The steam deck automatically outputs to the TV when you do this, just like the nintendo switch.