these just popped up on my M&S suggestions to buy: https://www.marksandspencer.com/silicone-stick-on-nipples/p/clp61230306
I must be getting old and out of touch because in my day we wore padded bras to hide our nipples through clothing!
and if I wanted to show some nipple these days (which I don’t) I could just wear a thin bra rather than stick these things on?!