I saw SpaceFish's message and tried uninstalling and reinstalling Google
Play. The Matter menus appeared. I had tried the same thing a few days
earlier and it didn't help. In both cases everything else was
up-to-date. Go figure.
Same issue - no options for adding matter devices. O/S, all apps and
security fixes are up-to-date on Pixel 7 Pro. Anybody from Google
looking at this?