I randomly said "Hi" and chatted very briefly about my kid and the apartment to a random young woman in the elevator. On the way out she literally did a little hop and a skip and in a chirpy tone she said "Yay! Interaction!"

I realised that after the COVID lockdowns people were so starved for contact with other people that any interaction would make their day. You don't need a pandemic for that, you can always make peoples' day just a bit better by saying hello.