Maybe she left it ambiguous for our imaginations. I read the book as a kid and just watched the movie on netflix. I personally think Jonathan found the physical place that was outside the barrier and they saw him as one of those secluded community people. They never thought they'd see him so they ask him all kinds of questions about life in the community. After a couple days he goes back and is treated with a whole new world. A normal world. That's what i think anyway. I like to think it all worked out well for them. Maybe it has something to do with me having a baby brother named Gabriel and just hoping he makes it through anything. Idk
This is the first part of a Quarter that Louis Lowry made. It goes The Giver, Gathering Blue, The Messenger and then finally, Son. All of them don't look connected, but the final book she released sometime around 2018 ties it all together. The ending isn't ambiguous at all.
The vibe i got is that in jonas's last alive moments, he realized that the idea of singing and music will never return, hence the "perhaps it was only an echo" and the whole "across space and time" I thought it was insinuating that that was a thing of the past and it would never come back but I think I was wrong