I expect that Nikon has patented the electronic coupling for their new lenses, so it may be difficult to get around. A simple tube with no electronics will be easy, and its possible that pass thru contacts for the "G" lenses may work.
Likely the same for RF mount. Manual focus lenses will work fine, but unlikely to have decent AF adaptors. Fortunately what is quite likely is that someone will do a Nikon G adaptor for RF mount that has an aperture control wheel on it. That would certainly be possible.
It's also possible that someone could do the reverse for the Nikon Z mount and do an adaptor that has an aperture control wheel for EF lenses.
The only issue in both cases is that this will only work if the mount can supply enough power to operate the lenses and the adaptors without it recognising a valid lens attached. They may both disable, or severely restrict, power until a valid lens is attached.