As a rule of thumb, I find Zig projects often come across as higher quality than many C, C++, or Rust counterparts — it’s a surprisingly strong community. That said, I don’t write much in Zig myself, haven’t explored the projects you linked in detail, and wasn’t even considering Zig alternatives as I needed something for my C++ and Rust projects.

From a first glance, they seem to be tackling a slightly different problem: focusing on efficient handling of nested parallelism. Fork Union doesn’t support nested parallelism at all.