Successfully tested with Ubuntu 20.04 as the host OS in 2 quite different "environments":
- Intel NUC machine (bare metal) on my desk.
- Google Cloud Compute Engine instance:
- Instance type: 'n2-standard-2', 8GB RAM, 2 vCPUs (Intel Cascade Lake), 10GB disk
- Nested virtualization enabled as per docs:
- https://cloud.google.com/compute/docs/instances/nested-virtualization/enabling