Does Vortex sell a killflash/ARD product for the Viper PST Gen II 1-6x24?

If not, are there any third party product recommendations?

I have seen them before but my google-fu is not coming back with results I am familiar with.  My 2 cents are a kill flash on a LPVO is not going to be a benefit in anyway you are going to lose a lot of clarity and make the optic really dark.  I have had kill flashes on optics as low a 40mm objectives and they get really dark and distorted.  If you are that concerned with scope glint/reflection install the sunshade included with the scope.

Thanks for the advice. Never had a killflash to experiment with.

I have had them on previous scopes and have taken them off very shortly after.  They will make the optic kind of dim and smokey like appearance while losing a lot of clarity.  I could see if you life absolutely depended on not being seen why you might want one but a sunshade will cover the objective for 99% of the possible scenarios where you might have a glint/reflection where the 1% is you looking towards the suns direction low on the horizon.
Just me but the benefit of a killflash does not outweigh the losses you incur from having it.  Save your money and invest in good scope caps.