Currently, clients tend to use a variety of mechanisms for observability. DataDog, Elastic (ELK), and New Relic come to mind as popular approaches. Each come with a JavaAgent approach to instrument the runtime and emit trace information (and in most cases, aggregate logging) to a central APM for inspection.
It is on the 2024 Broadleaf roadmap to include OpenTelemetry support directly from the Broadleaf stack with more prescribed tooling for observability in the reference implementation. However, this would not preclude other observability choices (such as those mentioned above) should they be preferred.