Some NetBSD 9.0 history. Why was this such an important release?

It was the first to run on arm hardware in 64-bit mode, i.e. aarch64. It already supported UEFI booting and S905/RK3328/RK3399/A64. Since then it's become one of our most popular and well-supported archs.

It added NVMM, which allowed hardware-accelerating QEMU VMs on x86.

It added tons of new security / QA features, including kernel address and undefined behaviour sanitizers.

It contained our first production-ready ZFS port.