The touchpads, virtual menus, layers / action sets, and overall control customizability really make the Steam Deck shine. PC Games with complicated keyboard-centric control schemes can be adapted to the Steam Deck so easily.
A handheld without that is going to be a hard sell for me no matter how well it performs. As a secondary device to a Gaming PC with a strong internet connection, cloud gaming makes my Deck handle whatever I can throw at it.
In terms of storyline, it doesn’t really matter too much.
I still think you should play through the first one. If you need something that feels less 1998, Black Mesa is a remake of the original Half Life and it is very fun.