There is currently no way to do this. In fact I think may be the first time it's been requested, most want the logo to link home it's very common UX.
I'll look into adding an option for this in the future. You could always create your own nav bar with a structure Bloc, image bric and vertical list with its data feed set to primary. The only downside to this is, the list wouldn't auto collapse on desktop so you would need to create a separate version of the nav to show on mobile with a button instead of vertical list that has a drop down with its data feed set to primary.