I’ve used it for two in person Craigslist/Facebook purchases and was paid for 3 different gear sales over the last couple years from people that didn’t want to use PayPal. I would not buy anything via the internet with it unless you trust the seller 100%, zero buyer protection.
From their site - “Unless directly given the option by Venmo, DO NOT USE VENMO TO TRANSACT WITH PEOPLE YOU DON’T PERSONALLY KNOW, ESPECIALLY IF THE TRANSACTION INVOLVES THE PURCHASE OR SALE OF A GOOD OR SERVICE (for example, concert tickets, electronic equipment, sneakers, a watch, or other merchandise). These transactions are potentially high risk, are not allowed under Venmo’s User Agreement, and Venmo does not have a protection program for such transactions unless directly offered.”