Noob needs help with google images add-on

I am new to firefox add-ons. Never made one before. I am a C# programmer, and I don’t have JS experience, so I might need some baby steps.
I need to make an add-on that either scans all the links in google images or detects a click on a link and re-processes it before linking you.
Here is an example link:

It needs to take the imgurl= link and remove percentages and then either open that link when clicked or replace all links on the page.

Pretty simple. I’d even offer a small compensation if someone made this add-on for me, but a bit of help is still appreciated.
I know there are add-ons for “view-image” on google, but I want a no BS link directly to the images the way it used to work back in the day. Now when I click an image, it takes me to the website and then I need to find the image on the site and often times, it is not right-clickable, so I can’t actually get to the original image file itself.

Hi Paul, just one note for your project:

The % indicates URI encoding. After you have extracted the imgurl string, you can turn that encoded URI back into a usable URI with the decodeURIComponent() function.

Also, if you want to iterate on your script code, you could consider using a Userscript engine such as Tampermonkey, Violentmonkey, or Greasemonkey. Then you aren’t dealing with the overhead of creating an extension, but just the manipulation of the page.