Magento 2 custom child theme add favicons
Ok, so the answer is that href needs to be replaced with src. Also you need to place or copy the normal favicon.ico file inside the theme_dir/web/ directory. All my other icons are in theme_dir/web/icons/
The following now works for me:
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<head>
<!-- Custom Favicons -->
<link rel="apple-touch-icon" sizes="57x57" src="icons/apple-icon-57x57.png"/>
<link rel="apple-touch-icon" sizes="60x60" src="icons/apple-icon-60x60.png"/>
<link rel="apple-touch-icon" sizes="72x72" src="icons/apple-icon-72x72.png"/>
<link rel="apple-touch-icon" sizes="76x76" src="icons/apple-icon-76x76.png"/>
<link rel="apple-touch-icon" sizes="114x114" src="icons/apple-icon-114x114.png"/>
<link rel="apple-touch-icon" sizes="120x120" src="icons/apple-icon-120x120.png"/>
<link rel="apple-touch-icon" sizes="144x144" src="icons/apple-icon-144x144.png"/>
<link rel="apple-touch-icon" sizes="152x152" src="icons/apple-icon-152x152.png"/>
<link rel="apple-touch-icon" sizes="180x180" src="icons/apple-icon-180x180.png"/>
<link rel="icon" type="image/png" sizes="192x192" src="icons/android-icon-192x192.png"/>
<link rel="icon" type="image/png" sizes="32x32" src="icons/favicon-32x32.png"/>
<link rel="icon" type="image/png" sizes="96x96" src="icons/favicon-96x96.png"/>
<link rel="icon" type="image/png" sizes="16x16" src="icons/favicon-16x16.png"/>
<link rel="manifest" src="icons/manifest.json"/>
<!-- Custom Metas -->
<meta name="msapplication-TileColor" content="#ffffff"/>
<meta name="msapplication-TileImage" content="icons/ms-icon-144x144.png"/>
<meta name="theme-color" content="#ffffff"/>
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1.0, user-scalable=no"/>
</head>
</page>