As you can see, in the red I want this area to scroll vertically, so that I can add more information onto the page, and keep the left navigation bar available at all times. Then, by using my navigation bar on the left I want to scroll to the relevant areas in my highlighted group (as shown).
You could probably achieve the desired effect by using a Floating Group for the sidebar. It’s not a very responsive solution out of the box if you want to use it on a mobile, but it is possible to achieve with some extra effort and page redesigning.
I’ve made an example project which you can check out here:
Site: Bubble | No-code apps
Editor: Menuscrollexample | Bubble Editor
Notice how I’ve used a multitude of groups that collapse when the page width decreases.
To scroll to a specific element, you could then use the built-in “Scroll to” workflow element. You can also test this out by clicking on the “My sidebar content” button on my test page