Your example is "one-level" side nav. I suggest to look at "two-level" side nav.
Two-level side nav can be done in 2 ways. Expandable or both main and sub menu visible. I have found that side-by-side is simpler to use on mobile.
An example of two level menu with accordions that can be used as an instruction step by step. So it is a 3 level menu sort of...
