The proxmox interface let’s you make the containers, but you have to install the software you want to host in that container after creation.
These scripts let you run a script that makes the container and also installs what you want to host within the container and does the setup.
I used their script to set up a home assistant vm, you run the script and it downloads the HaOS install media and does the install in the VM for you, preconfigured, and starts it so all I had to do was go access the web interface.
If you haven’t fallen down the keyboard rabbit hole then you don’t know just how far it goes…
It very much can be a hobby costing thousands of dollars and resulting in several keyboard projects.