Hi @JonaGsson,
The Earth mobile app currently only supports adding imagery and raster data from a service url or from online portal items. We plan to add support for local raster files including JPEG and JPEG2000 in a new release later this year. Stay tuned! You can try viewing the file on Windows app for now (https://www.esri.com/en-us/arcgis/products/arcgis-earth/downloads).
Regards,
Joe