I installed a Gollum server with an improved OmniGollum plugin with a design for acces to web folders as an extranet for clients.
Here is the code I contributed to OmniGollum
Here is the guide I followed
I documented the whole thing here
Update, I just pointed the content of gatsby.mann.fr to the gollum.mann.fr. That means that I can edit through the web a staging version of my new website. Yes! It is a little slow though.