Based on personal experience, the "friend" with a Mercado Libre account should be able to have any items you buy sent directly to you (in your name and to your address), provided they enter your information when they make the purchase, which as Rich indicates, you can pay for in cash at Pago Facil.Perhap, use a MP account from a friend, then arrange delivery near you and pay cash at Pago Facil. Precaria will do.
There are some online sites who sell online without using MercadoLibre or their hosted platform at MercadoShops. Either completely independent, or more common are those using the TiendaNube platform. I have found that these independent sites have the ability to change the billing country, and when you do you can enter another ID such as a passport (which is never verified except for delivery, if even)To register for a Mercado Pago account it seems you need a DNI. Does anyone know of any other way to create an account as a foreigner without a DNI?
So ignore my answers if one reason you want a MercadoPago account is to keep a saldo balance to make payments similar to how you might with PayPal or Venmo balances In the USA. Though if you need to make a payment with or without MercadoPago as the ACH, there are options.