As I understand it, these kind of applications depend on being able to perform activities in the background, which is highly limited in iOS for battery efficiency reasons--and maybe for privacy.
Many years ago I was working on a project that shared connectivity details over wifi/bt, and iOS was troublesome also due to the application not being aware of the local bluetooth address.
Possibly similar issues impact other mesh networking applications on the platform.
FireChat was a tool for revolution. Then it disappeared. ( www.fromjason.xyz )