Ich,

One approach is to have the Hamburger icon point to a separate menu page which scrolls the same as any other; this could be embedded into a popup menu too:

e.g.> https://initiostar.co.uk/demo/list-Test/

There are I'm sure alternatives to this approach and some might consider two vertical scrolls bars on the same mobile layout not a good design principle. In which case the hamburger icon could point directly to the menu page.

This approach has been described as a listings page and works as explained here: https://initiostar.co.uk/demo/iframe-links/ (explanation only in this example).