The cited startup time is better than Firecracker but it's not a better tool than Firecracker (for a start only claims to be a PoC, "contains only the necessary

The cited startup time is better than Firecracker but it's not a better tool than Firecracker (for a start only claims to be a PoC, "contains only the necessary parts for realistic benchmarking"). Looks like it's based on RISC-V emulation so the approach seems unlikely to get performance comparable to Firecracker. You might look into gVisor if you're running containerized workloads on a host without virt support (such as a vm without nested virtualization support).