Plugin example in V4.0 to override a controller/UI...

Hi,
I'm looking to add new functionality to the Customer controller by adding new methods and new UI components.
So far I've seen other posts that suggest what to do, but I must be missing something as I can't get anything to work.

Does anyone have a simple (complete) example plugin that shows ALL the code changes required to make changes to an existing controller/UI for nopCommerce V4.0? It doesn't have to be complicated, just adding a single word to a page would suffice. I'm just looking for a step-by-step example of what I need to wire up everything and make it work.

I really think it would massively help developers if this type of code example/documentation existed, or if it does, then to pin it somewhere to make it easy to find.
Many thanks.
Steve

Yes please, an example would be great. I need to convert from ActionFilters I used
now to ... what ?
The Middleware Documentation gives me a headache on how to transform this into Nopcommerce

review this post , it will help you.

Thanks RAJUPALADIYA, I did see that post.
I've followed this and many other posts to get so far, but now I don't have any styling to my new page, so I'm not sure I'm doing things the correct way.

As I said before, a complete (but simple) solution for a plugin to modify existing functionality (e.g. customer, or product) to help developers get started would save a massive amount of time.