Getting RGBA colour from gutenberg colourpicker

If you mean wp.components.ColorPicker which is based on react-color, then the tint object also contains a rgb property with an object of the RGBA value like {r: 51, g: 51, b: 51, a: 1}.

So in your code, you can use:

style={{ backgroundColor: `rgba(${tint.rgb.r}, ${tint.rgb.g}, ${tint.rgb.b}, ${tint.rgb.a})` }}

And an easy trick to know all the available properties in the color object is by running console.log( tint ).. 🙂