"Demasking indoors is still in transition: in restaurants yes, in grocery stores no. That makes little sense,.."

Actually, it makes a lot of sense. You don't have to take your mask off to shop, but you do have to take it off to eat. In a grocery store, you are standing with strangers; in a restaurant, you are sitting with people you know (bars are a different category).

In the grocery store, masks protect the unvaccinated from each other. Vaccinated people wear masks in grocery stores so that dangerous unvaccinated people cannot hide among the "safe" unmasked vaccinated crowd. This choice has nothing to do with transmissibility; it's all about protecting unvaccinated people from cheaters.

At some point, however, the vaccinated stop caring about the unvaccinated's exposure to cheaters, because the unvaccinated could be vaccinated if they wanted to be. Then, like a school of fish turning together, the vaccinated stop acting to protect the unvaccinated from each other. https://remarklj.medium.com/to-mask-or-not-to-mask-7193bc03d2ee