For xz, you need to compress with chunking (and may be indexing for more benefit), in order to allow parallel decompression to begin with. Otherwise xz produces a blob which you can't split into independent parts during decompression, which makes using many decompression threads pointless.

But yes, if parallel compression is creating non determinism, you can do all the compression work with chunking without parallelism, still allowing parallel decompression. But I'm not sure why it even has to create non determinism in the first place.