curious, the article mentions being able to view passwords but I wonder if their is wider functionality like autofill. if any Apple Watch owner with at least series 3 and Catalina can confirm that would be great
Well, it's a mixed bag.
Per the article, yes, can go into Safari > Preferences > Passwords and view the list after double tap of side button. As for auto-fill, not that useful, imo, and hence does not seem to be implemented, as need to select a password item first (eg. might have multiple entries for same site in Keychain).
Just tried Notes. Not as smooth. What finally got it to work, sorta, was to enter the password once. From then on, watch can open the note(s). But might take a couple of attempts before Notes registers the double tap.
However, depending on how you setup your accounts on Mac, might not always work. For example, I have an "everyday use" account and a separate admin account. I tried to turn on "Find My" on the Mac, buzzed the watch, double tap, nothing. Noticed the notification on the Mac said something akin to "use watch or enter admin credentials". Since my admin account is not tied to my Apple ID, a "mismatch". Had to enter the admin account name/password. Oh and: also have setup Settings to require admin account to unlock the panels.
ADD: just had the situation where I visited a site that does not use https (zap2it.com) and the option to set an exception for that site was offered via the watch.