HeadSpin https://www.headspin.io/ provides a large set of real Android and iOS devices distributed around the globe. Testing on real hardware is always better than testing in an emulator, and testing in a real location provides additional data points that help you eliminate performance issues with your application.
Testing just mobile web browsers is of course supported, but if you ever have the need you can test native game engines and get video and network performance statistics at the same time. Automated testing via Appium is natively supported, or you can bring your own framework.
We are a 40-person startup building a global platform for testing mobile applications, and gaining insights into their inefficiencies. Companies test their applications on real devices distributed around the globe on our network, and are able to measure a wealth of information about the application's behavior.
Testing just mobile web browsers is of course supported, but if you ever have the need you can test native game engines and get video and network performance statistics at the same time. Automated testing via Appium is natively supported, or you can bring your own framework.