Not dumb, it's something people run into a lot so good on you for being prepared.
The best option is to purchase direct from Google, as those devices are carrier unlocked and OEM unlockable. If you're in the United States then I believe buying from Best Buy is also a safe bet. There are retail options in Europe as well, searching the forum here can probably find you some useful results.
Online stores are incredibly hit-and-miss. Many sellers advertise unlocked but are only referring to carrier unlocked and are not OEM unlockable. You can always ask the seller but in my experience they don't know what it means nor do they care to check for you.