For others, why it may be useful in regular sysadmin job:
* say doing Ansible scripting against LOCAL network is hell amount of time faster than against 300+ ms remote machines
* note that because you can use VE snapshots, it's very easy to ensure your playbook works fine without guessing what have you modified when testing things - just do rollback to "clean" state and start over
* multiple distros available - need to debug Haproxy from say Rocky 8 linux? Check!
But Firecracker is fundamentally different because it has a different purpose: Firecracker is about offering VM-based isolation for systems that have container-like ephemerality in multitenant environments, especially the cloud. So when you use Firecracker, each system has its own kernel running under its own paravirtualized hardware.
With OrbStack and WSL, you have only one kernel for all of your "guests" (which are container guests, rather tha hardware paravirtualized guests). In exchange you're working with something that's simpler in some ways, more efficient, has less resource contention, etc. And it's easier to share resources between containers dynamically than across VMs, so it's very easy to run 10 "machines" but only allocate 4GB of RAM or whatever, and have it shared freely between them with little overhead. They can also share Unix sockets (like the socket for Docker or a Kubernetes runtime) directly as files, since they share a kernel-- no need for some kind of HTTP-based socket forwarding across virtualized network devices.
I imagine this is nice for many use cases, but as you can imagine, it's especially nice for local development. :)