The BFF diagnostics endpoint can be customized by implementing the IDiagnosticsService or by extending DefaultDiagnosticsService, its default implementation.
ProcessRequestAsync is the top level function called in the endpoint service and can be used to add arbitrary logic to the endpoint.
For example, you could take whatever actions you need before normal processing of the request like this:
public override Task ProcessRequestAsync(HttpContext context)
{
// Custom logic here
return base.ProcessRequestAsync(context);
}