It's not on the same level as the R Python ecosystem, but you should check out Scala. It has the power and flexibility, but also a fairly solid backbone of data science libs.
Without these it might be a a powerful tool, but it wouldn't be in the same niche as Python and R.
Also, having touched Scala once before, the complexity and learning curve, and the prerequisite of being knowledgeable about JVM ecosystem to be productive in it...
It's not the same as Python or R, you are right. There is complexity, but it's rewarding once you get past the initial curve. I felt similarity regarding the JVM, but again, it's not that bad. Plus with GraalVM you can compile binaries, which I love for so many reasons.