Don't think any plugs or dildos are specifically designed to be worn in public (at least I'never come across any). The problem that wanting to wear one in public poses is keeping it in place while you're in public and using your hands for other things.

I solved that problem by devising a makeshift harness for plugs or dildos out of two long bootlaces tied together with a little loop tied at the end of one. I run the harness through slits I've cut in the bases of my plugs/dildos and with the lace with the loop running up my back and over a shoulder. I run the other lace up my chest and pull the end through the little loop and down to push the plug or dildo up my ass then tie a slipknot in it to keep the laces tight and the dildo in place. Works great to keep the plug/dildo in place! Use it in public or even at home while doing chores!

Might not always be practical because of what you're wearing, but there should be times when you should be able to use it!

Used the harness to wear one of my seven-inchers to the supermarket! Felt so delicious that after getting what I needed I still went down every aisle just for the heck of it! I was wearing a t-shirt and cargo shorts and no one was any the wiser to either the harness or the dildo and the harness kept the dildo securely in place the whole time, even when I bent down or reached up for items.

So my makeshift harness can definitely be used to wear any rubber plug or dildo in public!