Custom Extentions?

I'm really not sure where this topic should live. It's related to web development, but not necessarily from scratch.

Anyway, I've always been a bit of a tinkerer. I started with SMF back in the day, and created some extensions (add-on's, customized codings, Packages) and I learned quite a bit about PHP development doing that.

Now I'm working with XenForo, and I'm learning all about OOP PHP development, and I'm learning a crapton about how XenForo is designed, and I'm really liking the layered templates the developers created as a framework. Granted, I'm pretty rusty at my PHP and JavaScript. It's been nearly a decade since I was last elbow-deep into it, so I am referencing the Internet quite a bit. And today that means AI assist-- I have thoughts and feelings about that, not all bad, but not necessarily warm and fuzzy either. I will say that using AI has really given me a direction to look in, once I see how it's constructing a piece of OOP code, I can follow along with it-- hopefully this isn't frowned upon.

Anyway, let's talk about some of the projects, large or small, that you've developed, to expand the out-of-the-box software you use. What were some of your prized achievements?