It it possible to share a Dovecot passwd file to use it with Postfix's virtual_mailbox_maps?

I run a small Postfix and Dovecot server with only a few mailboxes. All are virtual via Dovecot, there's no local delivery. Caused by the small number of users, I simply use plain text files for the password db and have configured Dovecot like this:

passdb {
    driver = passwd-file
    args = username_format=%u /etc/dovecot/users
}

The users file has the syntax

address@domain:{HASH_ALGO}somehash

To prevent backscatter, I set Postfix's virtual_mailbox_maps like that:

virtual_mailbox_maps = texthash:/etc/postfix/virtual_users

also using a plain text file, but this one has a different syntax:

address@domain somestring

Now I wonder if it's possible to directly use Dovecot's passwd-file for Postfix's virtual_mailbox_maps? Something like proxy:unix:passwd.byname?