You are free to install this script/stylesheet for yourself, but it is not allowed to be used wiki-wide (e.g., in MediaWiki:ImportJS, MediaWiki:Common.js, MediaWiki:Common.css, MediaWiki:Fandomdesktop.js or MediaWiki:Fandomdesktop.css), as it would violate Fandom's Terms of Use. (See the customization policy)
AvatarLink makes it where clicking on your avatar goes straight to your userpage.