Hello,
Just keep in mind that at the end of the day, you are just working with lists.
I would first build your page (or a page) using plain html/css.
HERE is a great css dropdown navigation. Once you have that working, start re-building using Wayfinder.
The biggest thing to keep in mind is that if you have several li’s with unique Id’s you will need to convert them to a number preceded with some text. (Because ID’s cannot start with a number).
Another bit of advice that I find helps when I’m stuck is start with the minimum Wayfinder call. That way every page shows up and you know it’s working. Then start putting in "filters" (include/exclude docs, start items etc.) to get the lists you are looking for. Eventually you will end up with the same html page you started out with.