It would be immensely helpful to be able to modify the HTTP request headers of the webpage widgets. This could be used in a variety of ways, but primarily useful for authentication purposes. Many web services can accept credentials passed via the "Authorization" header - Grafana and Jira Cloud are examples of this, both able to use Bearer tokens instead of standard usernames and passwords. It could also allow for access to sites protected with Basic Auth prompts.

Having this feature would avoid needing to write complicated scripts for some services, and result in a much more elegant way to display certain websites.