Your Steam Deck deserves a Deckmate. It's easily one of my most used and favourite accessories to pair up with a Steam Deck and now it's discounted so go grab it. They've actually done a bit of a rebrand recently, since they now offer up similar accessories for the ROG Ally too, so they're now known as Mechanism.
For those who haven't seen it before: it's an attachment system giving you a mounting system to basically mount…well, anything to it. Valve even used it for their video of the Steam Deck OLED orb in the official trailer, all those OLED's were mounted with the Deckmate.
It simply hooked over the top and bottom, and the mount itself is thin enough that it really doesn't get in the way of anything. Then you just hook whatever you want into the back of it. That could be a battery pack, a stand, a USB-C hub, attach it to a wall (because why not?) or whatever else you can think of that might need to be attached to it.
You can see my quick-take year-old video on it below: