I needed to have a readonly date field appear in my form with the intent of hosting a web map as an element in an experience builder map that integrated survey123 into the map's popup. the form was developed using Survey123 connect, and when i would test it as desired (thru Experience Builder) the date field was still editable. I finally got the date field to be uneditable by configuring my date field in survey123 as described below:
1) create a date field type
2) set appearance to Hidden
3) set readonly to YES and default to "today()"
then created a new text field type - set it to required and read only and set the entry in the calculation column to format-date(${date_field_name},'%m/%d/%Y'). solved my issue.
hope this methodology works for others trying to do something similar with different field types!