Often give or display a menu with prices.
What about alcoholic drinks in pubs or bars “2 pints of your best and a glass of house red”.
Alexa may not be great for purchasing from Amazon but this isn’t because humans have never shopped using only their voices. Nor is seeing things required.
Restaurants and catalogs have menus. Street vendors show you their goods.
You don't need to take my word for it. No one uses Alexa this way. The proof is in the outcome.