With your web site team. But as to your top question I do have a stance I'll share.
While I think some sites can get you to install an app for the most part people today will not install your app. Especially if it's for buying from your site. You would have invested time and money for an app few will install.
So the responsive site or even a mobile friendly site is the winner here.
Which one is better a mobile site or an app? I own a Magento eCommerce store. Should I stick with a mobile site or make a mobile app for the same? In case of apps, is there any Magento app builder extension?

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