Independent virtual desktops per monitor would be my most missing feature in Windows 10's implementation. Just something similar to the "Displays have separate Spaces" feature from macOS.
This was the #1 thing I was hoping this would provide when I clicked on the link. Basically stops me from even bothering to use virtual desktops on Windows, I got so used to having my laptop screen as a "persistent" desktop with stuff I always wanted to see on it.
Pinning stuff across all desktops is an OK solution for me. I just put Emacs up on my left monitor and it stays there.