I’ll always say the F.Zuiko 38mm f1.8 is a great vintage lens for your street photography.
It’s small, which keeps it discreet. It’s inexpensive, which means you can pick one up without feeling guilty. And the image quality is really good, which is really the most important thing.
I shot with mine in Ciqikou, in Chongqing, China. Come see how it went here.