The PS5's expansion slot takes a standard M.2 NVMe drive, but not just any drive qualifies. Sony sets a minimum sequential read speed, and a drive below it will be rejected by the console outright, so the spec sheet matters more here than in a typical PC build.
Beyond hitting the minimum speed, differences between qualifying drives are mostly invisible in day-to-day use — load times flatten out well below the fastest drives on the market. The decisions that actually matter are capacity, whether the drive needs a separate heatsink, and price per terabyte.
Below are the checks to make before buying, sensible picks at different capacities, and the questions people ask before opening up their console.