An EOSHD Forum member (thanks!) spotted this on a Chinese camera forum. It appears Z mount is indeed able to take Sony E-mount lenses with infinity focus and the adapter shown here features electronic contacts.
First 1.50 minutes is sample footage, you can fast forward to 1.50 for the technical info
Kickstart the HolyManta ND on FundedByMe
This is something I’ve wanted for a long time!
Focus and exposure are the most important things on a movie camera yet DSLRs don’t have a built in ND filter and you’re often left to shoot at ugly high shutter speeds such as 1/1000 in bright light to control exposure.
With this adapter you can add a variable ND filter wheel to any mirrorless mount camera (E-mount, Micro Four Thirds) effectively adding the main ergonomics advantage of the Cinema EOS C300 and Panasonic AF100.