It has been years since I played with it but OpenStack is a suite of tools to build a data center like AWS or Azure. You can get the VM bit up and running pretty quick with basic packages on an Ubuntu system if you want to play with it, but again it has been years.
What is your goal? Playing with kvm may be a better path if you want to understand virtualization.
If you want to upskill for a job, I’d see if there is a certificate to work on. Even if you don’t want the cert, the curriculum might be a good starting point.
To add, hypervisor is very low level, below the operating system often. Hypervisors allow you to run multiple operating systems on the same hardware.
Containers are isolated processes running within an operating system using stuff like cgroups.