Secret field should use 'password' type of field for hidding secret

It would be possible to create a new field that shows dots instead of its value

It seems a feature that should be implemented on a contributed project

Agree – I wonder whether this has the full behaviours desired (or the seeds for this capability) https://www.drupal.org/project/view_password →

@manarth That module seems perfect! A module would just need to use a password field, and let that module do the "hide/show" part.