Are all stainless steel plumbing fixtures lead free and safe for potable water?
Just to be a smart azz if you check prop 65 stainless has chromium way worse some say. 

To be truthful about lead stainless has no lead. Stainless has issues , have you ever seen a stainless boat? But for drinking water I would verify the seals were safe  more than the metal. but as far as lead I would not be concerned.

Just for fun ; 
For many years 60/40 solder was used with copper plumbing but back in the 70’s we changed to non lead solder on water pipes for copper but at that time plastic pvc and cpvc became the standard of it was not copper , prior to this it was galvanized, and prior to galvanized lead pipe was commonI have found lead water supply pipes in homes that were pre 20’s but mostly only drains after that time. 

To answer your question stainless will not have lead , but verify the seals are potable this is the maybe in my answer.