Unfollow everything & everyone on Facebook.

Unfollow.js

// Manual set-up
// click: ▼ at top-right
//        Newsfeed preferences
//        "Unfollow people to hide their posts" (also includes all Pages, which are not real "people")
// Scroll to the bottom of that so they are all listed
// Open console (f12, or whatever the fuck on MacOS) and paste these two lines:

var e = document.querySelectorAll("._5u3n");
e.forEach(function(elem){ elem.click() });