There are many games available for Steam Deck. Valve has tested over 13,000 by the end of 2023. Many work well and some have been re-worked to be better on Steam Deck. I look at the most-played games from Steam's own records and I might have played one of those. I don't leap for every US$59.99 game out there. In fact, I may never have paid that much for a game.
Here are my favourite games on my Steam Deck, in no certain order:
Asphalt 9
Ghostwire: Tokyo
Hi-Fi Rush
Spyro: Reignited Trilogy
Road 96
A Space for the Unbound
Heaven's Vault
Ni No Kuni Remastered
and just this week, Hogwarts Legacy
Supposedly, I have 81 games that are "Great on Deck" but I have installed 47 games on it, with a 1 TB microSD card, as well as internal storage. I'd really like to get one of those 1 TB m.2 2230 cards but I'm not spending more money just yet. Equally, I'm not interested in the OLED version of Steam Deck right now. This one is about one year old.
I was surprised at the performance of Hogwarts Legacy. So far, it's fine. However, most games are fine for me. I'm not a person who looks at the performance overlay to gauge whether I'm having fun or not. Let the people with a website do that.
If you just got a Steam Deck for Christmas, I hope you enjoy it. Don't expect everything to be as it was. Change with the machine.
Update 2023.12.28: I've seen that Hi-Fi Rush and Hogwarts Legacy got some love. Even Ghostwire: Tokyo, from Tango Gameworks like Hi-Fi Rush, got a mention here or there and A Space for the Unbound did, as well. I wanted to try Baldur's Gate 3 but it's too expensive and too big. I appreciate that it works on Macs but they changed their requirements several times and it's more-or-less just available for the most powerful machines. I had hoped for Divinity - Original Sin requirements, another of Larian's games that runs on Macs.