Couldn't see any option available for the TextInput widget to obscure a user's input for fields like password, etc.
https://developers.google.com/apps-script/reference/card-service/text-input
Couldn't see any option available for the TextInput widget to obscure a user's input for fields like password, etc.
https://developers.google.com/apps-script/reference/card-service/text-input
In the overview section of the CardService, It quotes:
“Currently you can only use this service to construct Gmail add-ons.“
So HtmlService is not available in constructing Gmail addon’s currently. And there is no option In the CardService object to obscure the textInput widget. The reference says when constructing your addon to keep it simple, nothing complex. You may want to rethink your use-case for your addon.