I recently picked up a mint condition 85/1.4 G for $1,000. Works great on my Z6 as well as my D500 (a pseudo 135mm f/2 on APS-C). The lens weighs 595g, and is 84mm long. When I add an FTZ to that on my Z6, it adds 135g and 31mm in length. So on my Z6, my 85/1.4 weighs 730g and is 115mm in length.
The new 85/1.8 S is 100mm in length, and 470g. So while the lens isn't a whole lot shorter, it is a good bit lighter (260g) than an adapted f/1.4 G. Of course, if you compare the f/1.8 lenses against one another, the new S lens is only 5mm shorter and 15g lighter. However, the lens is now "weather sealed", has 9 aperture blades (the 1.8 G has 7), has better coatings, and will focus faster & quieter.
At $800, it seems to be an OK deal. Sony 85/1.8 is $200 cheaper and 100g lighter, but lacks the weather sealing. Canon's new RF 85/1.2 is a monster, weighing in at over 1.5 MORE than the Nikon, as well as being nearly $2k more. You're paying an awful lot for that extra stop of light... However, for me, I'll continue to shoot my F-mount glass on an FTZ. Sure, it's a little bit bigger and heavier, but they continue to deliver excellent results and work just as well on my Z6 as they do on my D500.