So my question will be: 1. Is that possible to have vertical breadcrumb on webflow that can be collapsed and linked to CMS? 2. Also is that possible to the contributor to add new section/category via Editing mode?
In my opinion, you could do this via the cms.
But the only option i see if you want this menu on all the pages is tricky and not really the best for your client workflow.
You would need to create a main category, and add a single reference to those category (not multiple ref, single ref, if you have many ref you ll have to add as many fields as ref).
Also you won’t be able to catch a third category.
I mean :
You can’t do Main category ref to second category
Second category refer to third category
Equal Main category refer to third category
You ll have to do
Main cat referer to second cat
Main cat refer to third cat