Hello, welcome to the Microsoft community.
Thank you for your inquiry. The Surface Pro 10 also supports detachable SSD hard drives, so you can install the hard drive from the Pro 9 into the Pro 10.
However, since there are differences in the hardware between the Pro 9 and Pro 10, after replacing the hard drive, you will need to use a specialized image for recovery before you can start using it. Therefore, you won't be able to continue working immediately after changing the hard drive.
In addition, the Surface Pro 10 is currently only available in 256 GB, 512 GB, and 1 TB versions. There are no plans for a 64 GB version at the moment. If you need this version, you can keep an eye on our Microsoft Store.
Hope this information helps you.
Lugoo Bei | Microsoft Community Support Specialist