  Hadronic interaction models are a core ingredient of simulations of extensive
air showers and pose the major source of uncertainties of predictions of air
shower observables. Recently, Pythia~8, a hadronic interaction model popular in
accelerator-based high-energy physics, became usable in air shower simulations
as well. We have integrated Pythia~8 with its new capabilities into the air
shower simulation framework CORSIKA~8. First results show significantly
shallower shower development, which we attribute to higher cross-section
predictions by the new simplified nuclear model of Pythia.
