Is it possible to make a site like the one in this link in Grav?

I have been tearing my hair out trying to find a way to create a site a bit like the one in this link. It’s basically a very simple artist’s site. The only thing I want to do significantly differently is to have embedded video or audio on certain pages instead of photos. Is it possible to do this in Grav? The essentials for me are 1. a lack of clutter, and minimal explanation; 2. all the internal navigation down the left hand side on the desktop version, or in a hidden or collapsible menu in the mobile version; 3. the page you are on to be greyed out in the list of internal links on the left hand side; 4. it shouldn’t look like a work in progress the way that a blog is always a work in progress; 5. it should display simply and elegantly on phones as well as desktops.

Yes that’s very well possible. You can look into embedding video and audio in the documentation about media.
The requirements 1 to 5 are mostly handled by the theme of your choosing.