Stolen iPhone Motherboard Access Concerns

Hello,

My phone was stolen a few weeks ago and sent to China. I can still see it on Find My, I placed it on Lock Mode and Erased the phone. I got a message from someone in China that says “Your old iphone is recycled by us, we are just recycling merchants, we are not the ones who steal your phone, if you don't remove it, your old phone motherboard will be sold to other customers, maybe they will hack your phone or steal your credit card, or contact your family, so we recommend you remove it as soon as possible so we can restore the factory Settings and erase all data.”

Is this true? Can all my data be accessed through the motherboard on my old phone? Please advise. Thank you so much for your help.

[Re-Titled by Moderator]