Pythia 8 as hadronic interaction model in air shower simulations

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