A new third-party accessory for Xbox Series X could let you expand your system's storage without paying extra for one of the official expansion cards.
As spotted by Tom's Hardware and Hermitage Akihabara, the newly announced Sintech DIY CFexpress Card PA-CFEM2-C conversion adapter lets you plug your own M.2-2230 NVMe SSD into the back of your Xbox and use it to expand your system's built-in hardware. While making your own memory setup with the adapter - which is currently listed for $35.99 - could save you money over an official solution, this approach has two big limitations.
First, the adapter only works with short form factor M.2 cards. Second, while the adapter can be used with a range of cards meeting that form factor, Xbox Series X and S are only compatible with a select number of SSD drives that have certain firmware and internal formatting. As Tom's Hardware points out, you could use a Western Digital WD Blue CH SN530 just fine, but not a WD Blue PC SN530. In other words, put some time into researching compatibility before you try to save money on a storage expansion this way, or else you might end up with a card that just doesn't work.
It's also important to note that Microsoft only officially supports the one 1 TB storage expansion card from Seagate (though it looks like a 500 GB counterpart is also on the way). If you run into issues trying to use a third-party storage workaround like this, Microsoft may not be able to help you out with them.
If you need more room for previous gen games, you should also look into our guide to the best Xbox Series X external hard drives.