Can you just buy euros?

I'm curious, could you just go out and purchase euros as easily as you might buy something from a store? I understand that currencies can be exchanged, but is there a straightforward process for acquiring euros without having to go through a bank or a currency exchange service? I'm interested in understanding the logistics and potential limitations of buying euros directly, if such an option even exists. Could you elaborate on the process and any potential challenges that might arise when trying to purchase euros?