Customizing Bill Plan Page using Page Composer- dynamic authentication

Summary:

We have a requirement to customize the Bill Plan page and add a button that will trigger a REST API/OIC call to refresh the bill rates from our pricing tool.

Content (please ensure you mask any confidential information):

The plan is to use custom JavaScript within the HTML markup to call the REST API/OIC, passing the authentication details as a btoa (Base64 encoded) string of the Basic Username:Password. However, we are looking for a solution to pass this authentication dynamically in the SaaS environment (similar to how we use environment variables in OFS extensions).

Has anyone implemented a similar solution or have insights on how we can dynamically pass the authentication credentials securely in the SaaS environment?