It would be nice to have some "developer mode" metrics reporting when users are working with ZIO directly without using any metrics backend. This would likely be extremely minimal since we do not want to have any dependencies in ZIO (the existing developer mode server would not be in zio).

Possibly this could just consist of taking a snapshot of all the metrics recorded in the application at the end of the application and rendering them in a visually attractive way, or just providing an operator that allowed the user to do this themselves.