The guy I think you are referring to is Les Bosher. He makes one for the JVC GY-HD*** camera family and I think it may fit the Z7 which I think has the same mount plus a tiny panel of hot connectors which is recessed down a little below the flange surface.
I think his website may be
Les Bosher - Camera Engineer or something like that.
Using stills lenses on a 3 x sensor camera may cause some CA on junctions of hard contrast in an image.
The field-of-view for given focal length will be narrower going direct-to-camera versus going via the 35mm adaptor for the same lens. However there should be a contrast, light gain and slight resolution bonus.
You will not get any better shallow depth-of-field effect by going direct-to-camera with stills lenses over using the existing supplied zoom lens.
The 35mm adaptor will give you greater ability to achieve shallower depth-of-field for a given field-of-view or angle-of-view.