If you want to use the Warframe Companion App to view your inventory & world state from a SpaceNinjaServer instance, you'll need to patch the APK and setup the networking appropriately. The bulk of this is explained in the warframe-companion-patcher repository.

The only thing not covered is that the app will request many textures from SpaceNinjaServer, which in turn will look for them at static/data/PublicExport/Lotus/Interface/.... To populate them, you can:

• Export them from a game installation using Puxtril's Warframe Exporter.
• Download them from the internet.