Oh no, thats for app logs.
I haven’t had the need to use it, but for metrics, check out Fly’s built-in Prometheus scraper that can export metrics to whatever speaks Prometheus; ref: How To Use Fly Metrics and Feature preview: Custom metrics
Alternatively, you can opt to run Honeycomb’s OpenTelemetry agent along side your app process: Running Multiple Processes Inside A Fly.io App · Fly Docs
(For machines, instead see: Multi process machines).
I neither use honeycomb nor custom Fly metrics, so I may be way off here.