For which of these location data sources would you need to set up an account linked to Google Ads?

You need to set up an account linked to Google Ads for your Business Profile (formerly Google My Business) because this is where you manage your business's information that appears across Google, including Maps and Search. Linking it allows Google Ads to access accurate location data for features like location extensions and local campaigns, directly connecting online ads to your physical store. Google Ads is the advertising platform itself, not a data source. Google Merchant Center is for product feeds, not general business location data. Google curated chains are pre-defined groups of businesses, not something you set up an account for directly to manage your individual business's location.