I have a real use case! I have a commercial server software that can run on Ubuntu or RHEL compatible distributions. My entire environment is Ubuntu. They also allow the server software to run in a docker container but the container must be running RHEL. Furthermore, their license terms require me to build the docker container myself to accept the EULA and the docker image must be built on RHEL! So I have an LXC container running Rocky Linux that gets docker installed for the purpose of building RHEL (Core is 8) imaged docker containers. It’s a total mess but it works! You must configure nested security because this doesn’t work by default.
Instructions here: https://ubuntu.com/tutorials/how-to-run-docker-inside-lxd-containers#1-overview