Hi Franco,
For in-person transactions, and since cash isn't an option, I strongly advise against accepting any payment via Goods & Services. Stick with Zelle, or a Friends & Family payment via PayPal or Venmo.
A buyer can dispute a transaction if they've paid via Goods & Services, and PayPal/Venmo will only protect a seller in such a situation if there is proof of shipment and delivery. (I recommend reading this page for a better idea of the protections you're offered by selling via Goods & Services
https://www.paypal.com/us/webapps/mpp/security/seller-protection)
If you are going to use Zelle, check with your bank about daily transaction limits for the platform. And as Ted mentioned, the first transaction with a new payee will likely be limited to a small amount (or even denied outright). Roberta's idea of a $1 test transaction a few days beforehand is a good one.
Like Shawn said, I've never heard of being able to retract a F&F payment. G&S is the payment method a buyer would choose if they seek buyer protections when purchasing. I'm not sure why a buyer would need those protections for an in-person transaction, and if they insist on paying via G&S, that would be a red flag for me.
Personally, in your situation, I'd opt for Zelle as my first choice, with PayPal or Venmo F&F being there as a backup.
Danny
Madison, WI