Gantry5: vertical menu in sidebar?

I’d like to use a vertical menu (multilevel, may be always expanded) as “brick” (particle) in a sidebar.
Within the gantry plugin this seems to be either rather tricky oder extremely simple - anyway I just don’t get it.

How can I realise this? Is the way to go to access the “menu data” from grav (how?) and apply some style?
Has anyone achieved something like this?

I gave up on gantry5 and extended the lern2 theme to get a vertical menu.