Hi @stefancvrkotic, I'm going to bother you one more time for more context. 
I don't think this is possible on Cloud unless the data source is set to the response from a GET request to the Retool API (/users ) available on Enterprise plan. On Self-hosted, admins can query their own db.The Select or Multiselect component should be able to handle this if the Data source is set to the query that gets users from the org.
A workaround is to create a db table with the emails and other info from our users. If we have this, we could definitely query such table and set the output as the Data source of a Select or Multiselect component.