Microsoft has announced that there will be two additional options to expand the Series X|S internal memory.
Through the continued partnership with Seagate, 512GB and 2TB Storage Expansion Cards for Xbox Series X|S will be available soon in all Xbox markets. The 1TB card already exists.
The 512GB card for Xbox Series X|S will retail for $139.99 USD and will launch mid-November. The 2TB card will retail for $399.99 USD and will launch early December. That is expensive as fuck, but fear not, the 2TB card will have a Designed for Xbox Limited Series badge, so it will be totally worth it.