This app was mentioned in 14 comments, with an average of 1.36 upvotes
Here is a google play app called After focus and Afterfocus pro. There are foreground, medium and background option for the blur distances.
Try using AfterFocus I find it the best out there. There's a pro version as well. Give it a try and see the magic.
Could use an app like AfterFocus to edit your picture: https://play.google.com/store/apps/details?id=com.motionone.afterfocus
I use the pro version of this, works really well for me.