What are the best mobile development approaches to cut the carbon footprint? To answer this question, this experience paper provides a life-size comparison of native versus cross-platform frameworks prevailing in the mobile software industry at the time of writing, namely Kotlin Multiplatform Mobile, React Native and Flutter. To do this, we collected metrics related to the package size, network traffic and battery drain issued by a boilerplate application developed following the different approaches. Our preliminary findings tend to show that the cross-platform solutions perform quite well.