Even if you can gather that PGO metadata a running application won't be able to adapt to changes in that data.

It works well enough for systems software written in C and C++, where Java still remains a niche option, even when it could deliver.

Java has many dynamic features where runtime optimization is required to remove the overhead. Virtual method calls are opt-out instead of opt-in, and there is an open world assumption. The possibility of doing stack allocation of objects depends on the call hierarchy (in the future it will get a bit easier with value objects). Also, C/C++ are not managed languages, therefore the effects of bad optimization don't hurt as much.

Depends on how many dynamic libraries or OOP features get used, or the C++ frameworks inspired by Smalltalk that predated Java by a decade.