I can't comment on the comparison with Docker for Mac bacause, honestly, I have never used it.
With krunvm, each session initiated with "krunvm start" is an independent lightweight VM. The maximum amount of RAM the VM can use is configured with the "mem" flag (or it uses what's configured by default), but the VMM will always try to use the minimum possible amount of RAM by returning the pages the guest is no longer using to the host (virtio-balloon's free page reporting feature).
That said, you can also start a single VM (using "krunvm start"), run podman's service ("podman system service...") inside it, switch to another terminal in macOS and execute multiple containers inside the VM using "podman remote" [1]. Now I'm thinking I should probably write a tutorial about this option ;-)
With krunvm, each session initiated with "krunvm start" is an independent lightweight VM. The maximum amount of RAM the VM can use is configured with the "mem" flag (or it uses what's configured by default), but the VMM will always try to use the minimum possible amount of RAM by returning the pages the guest is no longer using to the host (virtio-balloon's free page reporting feature).
That said, you can also start a single VM (using "krunvm start"), run podman's service ("podman system service...") inside it, switch to another terminal in macOS and execute multiple containers inside the VM using "podman remote" [1]. Now I'm thinking I should probably write a tutorial about this option ;-)
[1] https://www.redhat.com/sysadmin/podman-clients-macos-windows