Steam Deck: How to Install an SD Card?

Remove your SD card from the plastic packaging and insert it upward, as shown in the screenshot below. The SD card slot on the Steam Deck is located at the bottom-right corner of the device.

On Steam, go to Settings > Storage, and your new SD card will now appear next to your internal drive icon. Select your SD card, press "Y" to bring up the options menu, and choose the "Format Drive" option. Alternatively, you can perform the same task by going to Settings > System (scroll down) > "Format SD Card." This process might take a while, so sit tight. Once the formatting is complete, Steam will display a message indicating that your new SD card is ready to use.