This is a new project, but sadly as explained here, it is just a multi-user puppeteering gateway for Matrix users:

You write it your jid and password in a private chat, it connects to the XMPP server and creates a matrix room for each contact in the roster. Basic text messages work flawlessly in both directions.

Sadly Bifrost is almost unusable from the XMPP side. I really wish there was a nicer gateway from XMPP to Matrix.