@thomasescritt 64GB will be extremely restrictive for modern games, for example, Red Dead Redemption 2 is over 100GB.
you can expand the storage with affordable microSD cards (Samsung EVO Select 256GB is less than $40) but I highly recommend the mid-tier 256GB Steam Deck instead.
even SteamOS files such as the Proton updates take up a reasonable amount of space, so unless you’re planning to exclusively play smaller games, the entry-level model will fill up fast!