Best way to test new packaging concepts with shoppers?

For packaging specifically, I'd go with an online shelf test using something like Hotjar's click maps or a dedicated tool like Strikingly or even Debate.io — you get real visual attention data at scale. Focus groups are great for 'why' but people often say one thing and do another. Run a quick online test with 200-300 respondents first, then use focus groups to dig into the 'why' behind what you see.