I think there's a lack of features inside the Grid system to handle simple mobile responsive design. Other modern UI frameworks offer breakpoints and column sizes to easily handle the screen size changing.

Material UI:

React Grid component - Material UI (mui.com)

Offering multiple breakpoint properties to each grid row would allow for easier responsive design. The below code sets the column span depending on the screen breakpoints defined.

<GridLayout>
    <GridLayoutItem row={1} xs={12} md={6} lg={4}>row content</GridLayoutItem>
    <GridLayoutItem row={2} xs={12} md={6} lg={4}>row content</GridLayoutItem>
    <GridLayoutItem row={3} xs={12} md={6} lg={4}>row content</GridLayoutItem>
</GridLayout>