There are 3 repositories under esri-developer-summit topic.
Esri Developer Summit 2019 presentations for the 3D ArcGIS JavaScript API
Palm Springs convention center footprint for Esri DevSummit
Esri European Developer Summit 2019 presentations for the 3D ArcGIS JavaScript API
Esri Developer Summit 2020 presentations for the 3D ArcGIS JavaScript API
Repository for Esri developer summit presentations
Look through previous years conference slide templates.