Google Flutter is a cross-platform mobile app development framework that creates apps for Android and iOS. Flutter is similar to React Native in that it helps developers build apps quickly using hot-reload and component-based design. However, Flutter takes a slightly different approach in that it includes its own 2D graphics engine to draw the user interface. This means it can perform very well on older devices.
For teams that are considering React Native or other cross platform tools, we'd recommend trialing Flutter on a project.