The verification I'd be looking for immediately in-store would be "is this [product] or is this a brick?" - that once happened to me, with (for all I see sellers complain about excessively buyer-friendly policies) no recourse or compensation. If there's a more-complicated verification needed, the buyer could request that it be held onto until that's performed (elsewhere, if necessary). Verifiable chain of custody protects both buyers and sellers.

Not that a dodgy Gamestop merger is necessary for this, but I'd be (much) more likely to both buy and sell on eBay if it existed.