I just finished The Pristine Cut of Slay the Princess, and I fully agree that it should be the GOTY.
It’s amazing how different it feels when you play a really excellent game. With most games I regularly pause and tab out, to browse the web. With Slay the Princess I did not. It completely absorbed me, even though it was my second play-through.
I have to second what xavier666 said. Use it as-is, at least for some time.
The only thing I would recommend is, that if you plan to play a lot of non-Steam games, it might be worth to enable SFTP access, so you can copy games from your PC over WLAN: https://handheld.quest/posts/how-to-ssh-steam-deck/
(just beware to not have it enabled while in a public WLAN - or at least disable password-based login)
Oh, and in case you want to play DOS games, I’ve written a short guide on how to configure DosBOX staging in order to get MIDI music working: https://www.grois.info/posts/2023-02/2023-02-02-dosbox-with-midi-on-the-steam-deck.xhtml