In an earlier article, I shared hands-on practices for building a cross-platform application using Kotlin Multiplatform (KMP) and Server-Driven UI (SDUI). We built a simple application where the UI layout is fully controlled by the server, allowing Android and iOS experiences to evolve simultaneously without requiring frequent App Store or Play Store releases. In this article, we will extend that application by implementing end-to-end observability, enabling us to monitor both mobile and server-side behavior in a single pane of glass using OpenTelemetry.