Sure, you can add a microSD card to the Steam Deck's card slot, but if you want a more permanent boost, you can do that with a new M.2 SSD, similar to what's used in the PS5.

The iFixit guide below takes a comprehensive look at the entire upgrade process, starting with step-by-step instructions on how to safely remove the existing M2 SSD from your Steam Deck.

What you need to upgrade Steam Deck SSD I used an anti-static wrist strap, a Western Digital SN700M SSD, and a screwdriver set with a plastic pick and tweezers during this installation process.

That meant SSD speeds were significantly slower than the M1 model unless you opted to upgrade the storage. The same was true of the entry-level M2 Mac mini and MacBook Pros.