How do I test an app on multiple devices?
You can test your app with virtual devices the same way that you test it with physical devices. Simply select virtual devices when you select test dimensions to configure a test matrix. To learn more about running tests with Test Lab, see Get started testing for Android with Firebase Test Lab.
What is cross platform testing?
Cross-Platform Testing is the practice of testing a program or software across numerous platforms to guarantee that it works properly on all of them. Different web browsers, operating systems, and gadgets could be used on different platforms.