Audiobook with more story after the credits that’s about Sci fi/fantasy teenagers living on the street develop powers to help change/revolt their oppressive society

[Kristin]

I listened to this newly published book 4-5 years ago it was going to have a sequel. The one thing that really sticks out in my memory is after the final credits there was a surprise with more of the story where the boy gets another power and then flies ( described as how Superman would take off).
More of what my remember is that he was homeless and of the lowest caste/class and unexpectedly starts to develop power. He makes friends along the way who also develop powers. The little group starts a fledgling revolt against the system (the system doesn’t know they have powers) for the better which will end the caste/class system