Corsair, makers of some of the best gaming SSDs around, are back with a fantastic deal on this smaller form factor MP600 Mini NVMe SSD for £75/$95 from Amazon. It's a great choice for use in Steam Decks, the Asus ROG Ally, or other handheld consoles with NVMe 2230 slots - allow me to explain why.
The biggest thing about the MP600 Mini is ironically that smaller form factor. Normally NVMe drives like this one are produced in an M.2 2280 size, which refers to a drive that's 22mm across and 80mm long, but this drive is 2230 - 22mm across and only 30mm long. That allows it to fit into devices where space is at a premium, such as the Steam Deck - a physically larger drive just wouldn't fit.
What's also handy here is that adding a drive like this one offers a major upgrade over virtually every configuration of the Steam Deck available, both in terms of speeds and storage capacity. A 1TB capacity provides at the very least double the capacity than the top-level 512GB choice, and it's even better when compared to the base model 64GB option.
The base 64GB Steam Deck also uses slower eMMC storage that maxes out at 300MB/s, so adding the MP600 Mini can increase speeds by tenfold - it's rated for up to 4800MB/s in terms of both reads and writes, even though you'll probably see closer to 3500MB/s given that the Steam Deck is limited to PCIe 3.0 speeds. It's also faster than the SSD provided with the 256GB and 512GB Steam Deck models, which maxes out at around 2500MB/s. So no matter which model you have, you're looking at a significant upgrade.
The only thing to keep in mind with a Steam Deck SSD upgrade is that it's a bit more involved than slotting in one of the fastest micro SD cards for Steam Deck. You'll need to carefully take the Steam Deck apart following this handy iFixit guide, which walks you through accessing the internals, carefully removing a heatsink, disconnecting the battery and swapping the drive. From here, you can use a USB flash drive to reinstall SteamOS. If you've worked on a desktop computer or laptop before, then this isn't any more difficult - it's just a bit fiddlier due to the smaller sizes. I'd say it's still very achieveable, you just need a bit of patience and a few tools!
Summing up then, £75 or $95 for a drive as capable as this Corsair MP600 Mini to slot into your Steam Deck is a fantastic deal, and if you want to make a worthwhile storage upgrade, this may well be the deal for you.