It will output the customary erasing, making bootable, copying and done as all other macOSes before this:
Erasing disk: 0%... 10%... 20%... 30%... 100%
Making disk bootable...
Copying to disk: 0%... 10%... 20%... 30%... 40%... 50%... 60%... 70%... 80%... 90%... 100%
Install media now available at "/Volumes/Install macOS Monterey"
Now stick is ready. Either boot from it, or re-run the Monterey installed from App Store.
When all the I's have been dotted and T's have been crossed, you'll be able to log into your newly upgraded macOS and verify the result:
At this point disappointment hit me. The feature I was looking for, WebAuthN or Syncing Platform Authenticator as Apple calls it wasn't available in Safari. To get it working, follow instructions in Apple Developer article Supporting Passkeys. First enable Developer-menu for your Safari (if you haven't already) and secondly, in it:
Tick the box on Enable Syncing Platform Authenticator. Done! Ready to go.
Now I went to https://webauthn.io/, registered and account with the Mac's Safari, logged in with WebAuthN to confirm it works on the Mac's Safari. Then I took my development iPhone with iOS 15.2 beta and with iOS Safari went to the same site and logged in using the same username. Not using a password! Nice.
Maybe in near future WebAuthN will be enabled by default for all of us. Now unfortunate tinkering is required. Anyway, this is a really good demo how authentication should work, cross-platform, without using any of the insecure passwords.