Yes it's possible to write Java without any boxing of primitives or garbage collection, but one can't use any of the standard libraries and it's not really Java one is writing but a very restricted subset. I don't think these benchmark are particularly indicative of real world performance. But of course Java is still hundreds (thousands?) of times faster than Python.

It’s okay to do some allocations - it can be stack replaced, and even if it’s not, the cost is very negligible. The problem is mindless allocation, not allocation itself.