That's true, but saying there's no difference is just plain wrong, and that was LnxBil's point. If there's no difference for your use case, well good for you. But for many others there are, especially if there are open connections which should not get interrupted, page and DB caches which would be purged, ...
You can install Docker in a VM.
Also, if it runs in a Container it normally runs in a VM, vice versa is more a problem.
That's something
@corsinvest may want to answer, as for now it seems like they only support deployment over docker.
So, either just run it in a VM (easiest), or try to get Docker inside LXC (some made it work, you need at least the nesting feature on) or install docker on the PVE host (most intrusive, it should not kill anything of PVE, but we cannot really help if)