You can add extra fields using ACF. These will display in the user edit screen, but you’ll need custom coding in the user profile template to display the fields on the front end. You can configure Relevanssi Pro to index your extra fields, or if you don’t use Relevanssi, some custom coding will be required to the staff search template.
So far, we’ve managed to keep a controlled list of user fields. I’m currently developing new fields for Location and Building which will be available via a plugin. Longer term, we may add functionality for custom user fields but there are no definite plans for the moment.
Hope that helps. Do get in touch if you need any custom development.