When implemented. It's a weakness of Android that few developers take advantage of all the features - I suspect a lot of apps are made iOS-first, so if a feature isn't available in iOS, it isn't implemented on Android. I hope that iOS gaining this feature will mean it is used a lot more on Android, too.
https://play.google.com/store/apps/details?id=net.everything...
So it isn't quite the same, but nor does it require switching apps.
And then they complain that Android users don't buy their apps...
This works with AOSP Email and Gmail (maybe others as well).
That already exists in the form of "read notifications".
That's why I really like them. If I go away for 5 minutes in the middle of conversation, I don't have to tell the person about it, they'll see their messages were no longer read.