I would like to propose something.
Same model as some mail provider like mailbox.
in place of the master password, login with a pincode (which in place of being some number it could be a smaller password like 6 or 8 char) then one press of a button of the yubikey. All that in the same input area, not in a chain of screens.
- easier to manage and to remember
- safer way to access your vault from a unsecure host like public library and others. You won’t need to enter your master password which could become a real item to identify yourself.