I have seen that the Survey123 team has not allowed Java Script functions to be used in Surveys outside of an organization due to web safety concerns. My idea was could a safety precaution such a password protected survey forms be created so that users outside of the organization could use a survey that uses Java Script functions.
It could be similar to a password protected pdf where only users who have the password can open the form and use/submit data. Maybe it could be set up in a way that only email addresses that have had the survey link shared with them can access the survey once they enter the password.