I’ve just finished installing the current version to my D: drive using mklink as above. I needed to link several folders to keep it off my near-full C: drive:
mklink /j "C:\ProgramData\Docker" "D:\ProgramData\Docker"
mklink /j "C:\ProgramData\DockerDesktop" "D:\ProgramData\DockerDesktop"
mklink /j "C:\Program Files\Docker" "D:\Program Files\Docker"
mklink /j "C:\Users\xxx\AppData\Local\Docker" "D:\Users\xxx\AppData\Local\Docker"
The link sources on C: will be created by mklink, so make sure they’re not already there. Conversely, it does not create the target folders, so you need to make sure they exist.
I don’t know if this is the best way to do it, but it’s what worked for me.