Thanks, Jon. I rarely check the "Software Update" function on my old iPhone 6S and have that red notification dot disabled on System Preferences. This update goes all the way back to iPhone 6S. Look at the list of apps and hardware at this
Apple Support page. The top five rows all show the Sep 13 update. Looks like the only system NSO ignored is the TV OS! That's generally the best 'hardware' to ignore, IMHO.
BTW, I suspect Apple's severs will be hit pretty hard today. My update is the slowest I have ever seen. Very slow progress bar since ~70%. Strangely Activity Monitor shows the most active Disk process is "com.apple.
MobileSoftwareUpdate.Update
BrainService": 6.01 GB written, 21.76 GB read!