To “richard.brock57”, you can search for M.2 2230 SSD and you should find retailers including CDW, Newegg and Insight who sell these. Or you can look specifically for a version, such as KIOXIA BG4 (Kioxia is the rebranding of Toshiba’s SSD drive business). Unfortunately retailers do not yet sell the 1TB version (at least as of my writing this on May 12, 2020), so if you really want 1TB you can do what this fellow did:
https://dancharblog.wordpress.com/2020/0... who purchases the Caldigit Tuf Nano 1TB external drive and swaps the Kioxia BG4 1TB M.2 2230 SSD in there for the one in his Surface Pro X. Currently that drives sells for $219 on Amazon.
To “Ismail Akudi”, you can go to https://support.microsoft.com/en-us/surf... to download a recovery image of Windows 10 onto a USB drive and use that to set up your Surface after you’ve upgraded the drive. You can look at the instructions at the link; they’re reasonably straightforward.