To add to what zasgar mentioned, I just wanted to point out that our instrumentation-free approach does apply to JVM and Node/Python applications for many of the traces we gather. For example, we use EBPF to trace protocols like HTTP as the data passes through the kernel. By gathering the data in the kernel, these EBPF tracers are completely language agnostic.
We'll be publishing a blog post on this soon, so please stay tuned. In the meanwhile, this other post (https://docs.pixielabs.ai/tutorials/simple-go-tracing/) gives an idea of how one can use EBPF user-space probes to trace applications and system libraries.