This site (https://zonk.be) finally has the green “Secure Connection” icon. Was actually as simple as
wp search-replace https://zonk.be/ https://zonk.be/ thanks to WP-CLI. If I can do it anyone can do it, just get your site on SSL/TLS, easy peasy and free with Let’s Encrypt!
This blog/website is now SSL encrypted thanks to Let’s Encrypt! And it’s free!