Writing a Blog site
Let's write a blog website from scratch. We will use the minimum amount of libraries and frameworks. This is the best way to learn almost anything.
I have written a static website that is generated from Markdown files. It's a simple python script that does use a couple of libraries. I even redid that without any external libraries at all and with minimum amount of Markdown. The only problem with it was that I need to build it. So I must have access to the build system and a way to upload the Markdown files to the builder.
If I want to add blog posts from anywhere, then I need to have a web application and to store the blog posts in some kind of database.
But why PHP? To me, the language looks absolutely horrible. You need $ for variable names. You use -> instead of . to get object properties, the built-in functions are a mess and totally non-standard.
But PHP is everywhere. It is very easy and affordable to get a website hosted on shared PHP Plan, with a relatively generous MySQL/MariaDB database. If you want something like Python or Java or Go, then your almost only option is a virtual host. And these can be very expensive.
I've written COBOL and other languages before, so PHP should be no big deal. I hope :-)