Most clipboard managers don't store to disk but in memory, AFAIK anyway. And your link just shows some programmatic access? How do I access that as a user when

Most clipboard managers don't store to disk but in memory, AFAIK anyway. And your link just shows some programmatic access? How do I access that as a user when I press Ctrl+C? I suppose it's "useful" for things like password managers, but since anything can read the clipboard anyway it's a very limited protection. If something is so sensitive that you're using that special programmatic way of storing it then you should be using the clipboard but an actually secure mechanism.