Just an FYI to OP: If you’re looking to run docker containers, you should know that Proxmox specifically does NOT support running docker in an LXC, as there is a very good chance that stuff will break when you upgrade. You should really only run docker containers in VMs with Proxmox.
Just for completeness sake - We don’t recommend running docker inside of a container (precisely because it causes issues upon upgrades of Kernel, LXC, Storage packages) - I would install docker inside of a Qemu VM as this has fewer interaction with the host system and is known to run far more stable.