This will be available in the next version of the browser extension and desktop app. PIN can be any value that you want (unlike mobile app, which is 4 digits).
Ex:
PIN code usage will persist since it encrypts the master key on disk. If you ever fully log out of the application, the PIN code setting will reset, requiring you to set PIN back up again when logging back in. This shouldn’t be too big of an issue since most users never log out of the application.
5 invalid PIN attempts will log the user out (requiring master password).