Openstack is like self-hosting your own cloud provider. My 2 cents is that it’s probably way overkill for personal use. You’d probably be interested in it if you had a lot of physical servers you wanted to present as a single pooled resource for utilization.
How does one install it?
From what I heard from a former coworker - with great difficulty.
What is the difference between a hypervisor/openstack/a container service (podman,docker)?
A hypervisor runs virtual machines. A container service runs containers which are like virtual machines that share the host’s kernel (more to it than that but that’s the simplest explanation). Openstack is a large ecosystem of pieces of software that runs the aforementioned components and coordinates it between a horizontally scaling number of physical servers. Here’s a chart showing all the potential components: …wikimedia.org/…/Openstack-map-v20221001.jpg
If you’re asking what the difference between a container service and a hypervisor are then I’d really recommend against pursuing this until you get more experience.