The advantage of mirrorless designed cameras is the flexibility it gives you in lens design. Its because of this that we have seen some amazing glass coming from Nikon for the Z range.
Its also because of the short flange design that means you can use other lens on mirrorless cameras. Techart have now released their TZM-01 adaptor that allows you to not only use M glass in your Nikon Z camera but it also allows autofocus.
When it comes to manual glass I use some of my old Nikkor AIS manual focus lens with the FTZ Mark 2 adapter, but I was also treated by my lovely wife at Christmas when she bought me the Voigtländer M to Z Adapter, so you will start to see a few pictures taken with my Nikon’s using my Leica glass.