Custom properties for Retool users

It would be nice to be able to add additional properties to Retool users, that are returned within the current_user object (in addition to the currently available firstName, lastName, fullName, email properties). I see there is also a metadata property, but no apparent ways to add data into here? Otherwise that could work as well.

For example, I could use this to pass through an id for each Retool user that matches a primary key within my database, and avoid an additional query to get the primary key based on the

Welcome any better solutions as well. Thank you!