I am new to Grav, as well as new to using Nginx.
I am posting my experience on the install process.
Installing Grav and using the PHP built-in web server worked great, very easy.
I had issues when installing Nginx on Ubuntu that took me about 4 hours to correct.
For the record, I am not a web designer, web framework or coder. I am familiar with some web hosting, LAMP installs, general Linux, permissions, very good on Windows side.
That being said, the Grav install was not easy as in, easy for the general populace to install and use.
Through the frustration of the install, theme setup, a few plugin install I made a document that, if Ubuntu users follow it should work and save lots of time for them.
Just trying to contribute in some form or fashion.
On the AskUbuntu Guide Here is where the post is at. The resources used were Grav site, a blog article and some Nginx site into.
Hope it helps users using Ubuntu 16.04. May work on previous versions of Ubuntu or 16.10, or 17.