Fuschia is an extraordinarily complex kernel design. Hell, it's a "microkernel" which is bigger than Linux! It's fairly typical of Google's inwardly-focused engineering culture, using questionable tools (with large shadows) such as Bazel and gRPC, which were likely chosen simply because they plug into the Googler engineering culture. At the same time, these decisions give way to a very complex system with heaps of moving parts, in this rube goldberg design which is endemic of Google engineering.
Helios is much, much simpler. The kernel itself will probably clock in at under, say, 20,000 lines of code (for x86_64, at least), and it has a very small syscall API, less than two dozen in the final design. Many of the things Fuschia does in the kernel will be done in userspace on Helios, in the Mercury component, such as service discovery and capability allocation. Finally, Helios is written in Hare, which itself is a much simpler language than C++, and kernel hackers at the very least should be convinced of the argument that the complexity of your implementation language contributes to the complexity of your implementation.