Customer wants to purchase $500,000 car in crypto

I have a client that is selling a $550,000 car and have an out of state customer that wants to pay in USDC. He originally asked if I would take BTC or ETH but I suggested USDC. I wanted to make sure the transaction could not be reversed or see my risk level here. Please let me know if anyone here received deposits this large that can give me any tips and also make sure I don’t get scammed. How difficult will the withdrawal process be for this from crypto dot com to a traditional bank and what will be the fees associated? All communication has been online, their profile seems legitimate, but I am still always skeptical. The customer also states they have already sent $1,000 USDC test deposit to address.

I appreciate any advice, and also would take recommendations for any other currency that would be a better option compared to USDC . The transaction will have to go from the customer - to me - to my client, since the client does not have any accounts. Does this open me up to tax liabilities even if unrealized? Or is the client better off opening up a wallet for this transaction alone. Thanks!