Do I need to dielectrically insulate smart home shuttoff valve on water main?
They are not prone to leaking.  But since you are cutting into the water main inside the house (which I assume is coming into the house) you can go from the main to PVC then to your stainless steel valve if you like.  What is the material of the plumbing in the rest of the house?  Is it already PVC or PEX?