That’s true, bhyve doesn’t support nested virtualization right now.
In practice though, most setups don’t actually need it if you’re running workloads directly on the host.
Also, if your goal is testing or simulating clusters, you can already run Sylve inside jails. That gives you multiple isolated “nodes” on a single machine without needing nested virt. We have a guide for it here: https://sylve.io/guides/advanced-topics/jailing-sylve/
So you can still experiment with things like clustering, networking, failure scenarios, etc., just using jails instead of spinning up hypervisors inside VMs.
Nested virt is still useful for specific cases like testing other hypervisors or running Firecracker inside VMs, but for most Sylve-style setups it hasn’t really been a blocker.