What is the lightning equivalent to the classic collapsible sidebar?  We are converting users and they want to get items from Classic (specifically the narrow section "quick links") in Lightning. 

I don't want to create app specific home pages OR for the links to be specific to the app via the in-app utility bar.

I want the items from the Classic sidebar to be universally available to users anywhere on the platform BUT also different by user profile.

I have searched documentation and topics but can't find the answer... am I missing something incredibly obvious??  TIA