Current settings only allow assigning particular applications to a desktop, I would like to pin specific windows of an application to different desktops. I can do it manually with dragging, that works great, but gets annoying after a while 
There isn’t really any super good way of doing that - you could perhaps poll all the windows in the system and try parsing the names of the windows, it may not be totally reliable.
Some people have used the TotalSpaces2 API for something like this, but it requires a bit programming skill. See Feature request: