Are you allowed to embed a username/password form via an html code widget?

We want to integrate our core app's firebase login/registration step within a Jotform. Is there any sanctioned way to do this?

We do not allow login forms or form that asks username and password using our native fields. This is a violation of our terms. If you require that for direct integration with your app, you can add it as a widget. To create your own widget, this documentation might help https://developers.jotform.com/widgets

If it requires API, you can check out API Documentation here https://api.jotform.com/docs/