You can add boolean value to your entity e.g. IsSelected after it's select/trigger row you can add Dynamic row class that can add class to row based on your boolean value it should be something like this
if $currentObject/IsSelected then 'your-class' else ''
and to make sure you add task to be background you have two option inside on click microflow you can first change boolean vlaue from false to true and then exec submicroflow in TaskQueue or add it to Background task using Java action from CommunityCommons
Best regards, Slavko