And it looks like Cloud Run can do something Lambda can't: https://cloud.google.com/run/docs/create-jobs . "Unlike a Cloud Run service, which listens for and serves requests, a Cloud Run job only runs its tasks and exits when finished. A job does not listen for or serve requests."
Possibly? I haven't found any public documentation that says specifically what hypervisor is used.
Google built crosvm which was the initial inspiration for firecracker, but Cloud Run runs on top of Borg (this fact is publicly documented). Borg is closed source, so it's possible the specific hypervisor they're using is as well.
I believe that's an Intel project, not a Google project. I personally think it's more likely Cloud Run is on top of the same proprietary KVM-based code they use for their Compute Engine.