Hi @not6248 welcome to the forum!
There is no GSAP code in your demo, we love to see what you've tried already, that way we can see your thought process and thus better help you understand the tools!
Also if you want to get the most out of these forums... Keep it simple. Don't list a bunch of requirements ("it should ___, and ____, and then also ____ while _____ ..." - that's too difficult to follow). Just pick the very first thing and see if you can make that work. If you get stuck, post one question focused on that one piece, like "how can I pin each section one at a time?" Keep your CodePen focused only on that one piece with as little code/markup as possible. Then once that's answered, move on to your next question/problem.
If you're new to GSAP check out this awesome getting started guide https://gsap.com/resources/get-started/, also keep in mind the best thing to do when working with ScrollTrigger is to remove it! This seems counter intuitive, but ScrollTrigger is just animating something on scroll, so just focus on the animation at first and only when you're happy with the animation add ScrollTrigger back in. This way you can focus on one part at a time and it will save a lot of headache when debugging.
I've also written a guide how you can go about creating a card stacking effect, this will also work for panels! But as stated before you first have to create the animation before you think about ScrollTrigger also when working with ScrollTrigger it is beter to leave all the pinning and sticky-ing to it, instead of setting it via CSS.
We would love to see what you've tried and hope with this info you can find your solution, just post back here with a minimal demo that does have some GSAP in it and tackle one question at the time! Hope it helps and happy tweening!