The rise of in-store media and omnichannel strategies reveals a critical gap in retail media: standardized measurement. Brands collaborating with multiple retail media networks (RMNs) face the challenge of evaluating campaign effectiveness based on inconsistent metrics, hindering them from gaining a holistic view of their retail media investments and impact on customer experience. Since retail media is interpreted differently by different players, brands must prioritize data-backed investment decisions while aligning expectations across suitable vendors.