I tried looking around for info on a steam deck case that was horizontally compatible with the LTT backpack and couldn't find any pictures/guarantees online. If anyone is unfamiliar, they designed the backpack to fit the steam deck during its design phase, but they didn't account for the carrying case (it wasn't publicly revealed at the time). Since I got the backpack, i've had to throw my steam deck case in vertically, which took up a ton of room

I went ahead and snagged a Tomtoc case since its the slimmest carrying case I could find on Amazon, and sure enough, it fits like a charm!