This repository is a collection of third-party articles and specific tutorials on PHP upgrades, which can help us scaffold and find inspiration for the planned servehappy page for WordPress.org.
Note that hosting-specific tutorials are organized by language, in particular because there are several hosts that only operate in one or a few countries.
You are always welcome to add links to interesting and possibly helpful articles about upgrading PHP to this list of resources, as well as links to tutorials on how to upgrade PHP on a specific hoster, operating system or tool.
Every list page contains a Edit button that leads to an edit page where you can easily make changes to the respective file and then create a pull-request with these changes. For hosting-specific tutorials, you will also find a Add New Language button which you can use to add a new language if it isn't listed yet.