Many types of articles can be helpful to you to discover Gen Z consumer trends. Use filters within any of the tools below to limit to a certain type:
You will likely not find many (or any) articles specifically about Gen Z and pizza/coffee consumption. However, think about other search terms and concepts, such as Gen Z plus:
Communication, linguistics, rhetoric, media, & more
Global, national, & regional news
These types of sources will not have a survey specifically on Gen Z (or others') pizza or coffee consumption. But they should have separate statistics on Gen Z attitudes, fast-food or fast-casual dining preferences, and coffee preferences, from which you can glean information.
U.S. business-to-consumer market research & psychographics
Statistics & studies gathered by market researchers, trade organizations, scientific publications, etc
These will not address pizza specifically, but these articles collect various statistics related to Gen Z.