Accessories
From Retroid Handhelds
SD Cards
Theoretically, the RP2 should be able to accept any microSD card up to 2 TB in size. However, for cost and performance reasons, it is recommended to use a 512 GB or smaller card. Our communities recommend the Samsung Evo Plus or Samsung Evo Select microSD cards for the RP2. For a detailed breakdown on why these specific cards are recommended, see this post on our subreddit.
Cases
Confirmed to Fit Well:
Official Retroid Pocket 2 Case
Many 2DSXL or 3DSXL cases/pouches will work well, but they do vary from brand to brand, so you may not get a snug or exact fit.