In situ / operando characterization techniques are attracting considerable interest from the research community and industry, since they provide insight into the dynamical evolution of physical-chemical properties of functional materials under relevant, realistic conditions. During such advanced characterization experiments, an external stimulus is applied, while the properties of interest are monitored over time and space. Significant examples are: temperature control, variable pressure, electrochemical stimulation in conditions relevant for the applications. The data collected during in situ / operando experiments are essential for the development and validation of digital twins of the functional material, building a more accurate representation under working conditions. This predictive capability of the digital twin can guide new experiments, which then provide fresh in situ / operando data, forming a closed loop, resulting in accelerated design of advanced functional materials.