However i can’t find the solution to make it work on Firebae hosting. Firebase need an index.html which we normally have easilly on a web app OR a static content (which Grav is), how can i bypass that ?
Firebase hosting does not support any server side scripts such as Ruby, PHP, Python or anything else that is processing your files before output. That would require a application engine such as Google App Engine, Heroku, or similar.
This can be archived, so that anyone running in the same problem can quickly find a solution