Can’t remember which NDE book it was from, but I’ve heard discussions of one child who was clinically dead but revived. He said he was in Heaven and saw loved ones including a sister he described and named. He came back to life and told of it.
At first his parents didn’t want to discuss it but then revealed that they had never told him a sister of his had died in childbirth-—the one who would have been of the age he described.
Here it is:

Heaven Is for Real by Todd Burpo