Dear friends, after thorough research, we have to say that currently, there is no option to let your customers leave their reviews directly with a click on the button 
This restriction comes directly from Google, and for the moment there is nothing we can do about it. We, however, are going to keep tabs on the situation, and we’ll be happy to implement this feature as soon as any workaround becomes available.
Thank you so much for sharing your ideas and thoughts here! 