For those who are feeling intimidated by glares/stares when entering shops maskless, here is some help:
1) It's like working at the top of a ladder. First time I did, many years ago, joiner I was working with told me "make sure you have both your feet firmly on the ladder ... and DON'T LOOK DOWN!" That's where the fear is: if you're constantly looking around you to see who's wearing one, you'll get negative thoughts because 1) you'll be constantly reminded that you're the 'odd one out'. 2) You'll actually attract the very attention you wish to avoid.
So - just remember - at the very very worst - you can always walk out, if challenged, but that would be unlikely anyway. Once you have your confidence, it's time to turn the tables. This is what I did, this afternoon. I have a 1 minute recording of sheep baa-ing on my phone. I played at as I went into Sainsbury's local, maskless. There were about fifteen or so people in there, and they soon began to look around, to see where the sound was coming from. After about fifteen seconds, two youngish blokes just about to get served, realised it was a dig, and looked straight at me in a (dare I say 'sheepish'?) way. As they reached the till, they lowered their masks. Others in the queue looked very uncomfortable.