After having devoted several years to the study of the foundations of quantum theory and quantum information, the scientific interest of Brukner and his team shifted towards the understanding of the interplay between quantum theory and gravity. In order to achieve an understanding of these phenomena from unexplored avenues, they have based their investigations on the belief that physical phenomena must be described in terms of operationally well-defined notions, and have therefore employed quantum information tools and operational approaches towards this goal. Examples of frameworks that their research has helped to foster are the study of indefinite causal structures and quantum general covariance. Indefinite causality describes structures that are expected to arise in the context of quantum gravity, where the metrics, and thus the causal relations, are predicted to be influenced by quantum mechanical uncertainties. Instead, the principle of general covariance describes the idea that physical laws retain their form across different reference frames, and part of their research programme is to extend this idea to the case of quantum reference frames.