Catalina - install on a new Partition or new Volume?

If you have APFS, just create a new Container/Volume. It shares free space with its siblings.

 

I was under the impression that APFS volumes usually share an existing container and therefore are not bootable. Partition on the other hand creates a new container and is bootable. What did I miss?

 

Apple actually has a support document for using APFS Volumes to install macOS https://support.apple.com/en-us/HT208891 works fine and boots just done it today

 

They are bootable. There can be hidden size issues. I just added an APFS container to a larger disk and then realized that I needed more space on that new container. I deleted a bunch of files in the other did not free up the space I needed.
Note that the installer will create a second APFS container for the data portion of the install.

 

So in essence I could have a Macintosh SSD and High Sierra as bootable volumes both under the Container disk1? No need for container disk2?