Refer to previous posts:
https://whysun.com/x-box/xbox-series-x-exapnsion-ssd/
https://whysun.com/x-box/xbox-series-x-update/
I have weakened and purchased a 1TB Expansion SSD for my X Box Series X.
Prices have been reduced at retailers and the 1TB card is now for sale at AUD$289 (down from AUD$429-95). Retailers also have a 2TB SSD for $529 down from $749-95 but I am not paying that much.
I was given gift certificate for $130 at JB Hi-Fi so I only had to spend $159. Still expensive but, as I have said before, I have more money than sense. Also I could not think of anything else that I needed from JB Hi-Fi.
It was easy to install but I have kept my old USB 2TB external drive to store games. It is quicker to transfer games from an external drive rather installing again. An additional 1TB taking the total internal storage to 2TB is still not enough bearing in mind the size of new games. However, my set up of internal 2TB plus external 2TB (total 4TB) is a reasonable compromise.