The google merchant Center is one among the many tools available when creating a Google account. It aims to let you setup a merchant center where you can basically sell and make the products you sell visible in adds and shopping pages of the whole google environment, including Youtube or Gemini as of 2024 at least.
I have set one up to imrpove my E-commerce solution for PapierLogiK, and I gathered useful information related to this experience below.