We are currently running this site on 5 Raspberry Pi 4 (4GB) boards held togeather with Pi Cluster cases.
Currently running Ubuntu 20.04 with Corosync & Pacemaker for high availability in two two node clusters. The site is then load balanced with Apache Load Balancer on a round robin basis on a 5th server which allows us to use two floating ip's for high high availability. The website is mainly written in PHP and developed using Multipass as a development zone and then git pushed to Github and merged with a master branch. To deploy changes across all 4 servers we use Ansible Playbooks to connect with all 4 servers to pull changes.
Digital Certificates are provided by the superb Let's Encrypt
We currently serve about 40,000 pages a day and in total about 3.6GB of data a day.