This addon gives you the ability to add markers inside a webpage which will help you in navigating back and forth conveniently on the page. These markers are stored pemanently in local storage Working:

Press Ctrl+Click or DRAG the pin 📌 to add markers.
update: Closing or refreshing the page restores these pins.
update: Addon will open by default if it contains pins from previous session. Pressing [clear] button will empty the list and disables this behavior.
Click on the pin to hide UI
You can view its working in this video.

You don't have to worry about messing the order of items, this addon takes care of preserving the order of items with the webpage. You can also delete the markers if you like. Enable this addon by clicking on the icon after installing, you'll see the addon appear on the webpage. Remove it simply by clicking the marker again. You are gladly welcomed to input any of your suggestions here. Works on mobile (tested on Android). I created this addon as I needed something like this.

Usate per