You can buy all sorts of stuff if you have money burning in your pocket, but as far as essential goes, you’ve already got it all.
That said, you might want to get a multipurpose USB-C dongle, for connecting the deck to an external display, keyboard, mouse, ethernet and such. The Deck Dock is okay, but there are cheaper options with the same functionality.
You can buy all sorts of stuff if you have money burning in your pocket, but as far as essential goes, you’ve already got it all.
That said, you might want to get a multipurpose USB-C dongle, for connecting the deck to an external display, keyboard, mouse, ethernet and such. The Deck Dock is okay, but there are cheaper options with the same functionality.