Feedback to Canon on the Windows 10 Selphy driver installation:
After reinstalling the Windows 10 Selphy printer driver files and rebooting and getting it to work, I can see now that the first time the driver installation was attempted, the installer "creating folder" popup appears, but the "copying files" popup never appeared along with the copying progress "green" progress gauge. The installation never copied the drivers, and just said "installation completed". The second attempt attemp worked, because the drivers and configuration files were actually copied and installed, and the Selphy was useable at that point.