Ok, my bad. I just got off the phone with Nikon.
@Warren D was right The Z6iii under Custom Settings, D Shooting/Display, d6 shutter type by default is set to Auto. Auto in my case results in Mechanical Shutter which disables Shutter sounds per Nikon. I realized without prompting my Z8 has no mechanical shutter, the sound always works. Duh....
My Z6ii had a nice thump during the shutter release, so the sounds or lack thereof never came up.
So for wedding photography, Silent mode is just a shortcut for electronic shutter without digging down to d6 in the Custom settings I take it AND without the shutter sounds if enabled along with Beeps. Someone
@Cameron T can jump in to point out what I missed.
d6 menu options are Auto, Mechanical, Electronic front-curtain, and Electronic Shutter. Auto being the default, I am sure some extended speed goes to electronic but that is not where i live shooting plodding subjects.