There are some installs that would use such as drive as dual purpose. Possibly why you only saw part of the drive.
Can a 32 GB SSD be used to install Windows 10? Physically yes, but I would not advise that unless you were going to use that OS to just play and not a primary install. Such an install would not be able to be upgraded since it would not have enough available space on the drive.
On my system, I replaced the 32 GB drive with a 250 GB and moved the OS install to that. Currently this install takes up 100 GB of the 250 GBs..