I used the original source of @infobeamer-fw to create a version which has support for custom headers. This allows you to add an Authorization header with Basc auth or a Bearer token for example.
See: choeflake/infobeamer-fullscreen-browser-package (github.com).
For example Grafana has support for showing dashboards with an API key as Bearer token in the Authorization header. This eliminates the need for anonymous dashboards.
@infobeamer-fw Could you integrate this into your version of the Fullscreen Browser package so that it is available for everyone by default.
Great work. You now probably know more about the chrome dev tools protocol that I do 
I just looked into how you’ve implemented this. It seems setExtraHTTPHeaders is the key. What I’m not sure about yet is whether or not doing it this way isn’t potentially quite dangerous: From what I understand the browser then adds the configured header to any request send to any resource issued by the page. I guess it would then also include the header in any third party resource request, be it scripts or images from potentially untrusted sources like counting pixels or ads.
Or maybe I’m misunderstanding how this works. Is there a way to limit the sending of custom headers only to the initial page navigation?
Good point! I will have a look how to mitigate this issue.