If you did this you might not know about the Proxmox Helper Scripts: https://tteck.github.io/Proxmox/
It has a bunch of scripts to help setup and maintain containers. This use case should be covered by the "Proxmox VE LXC Updater" in "Proxmox VE tools" group.
Looks fine. You might save some money on the PSU by choosing another one from A tier here and by lowering the wattage. ~800W is more than enough for that build and for the future
Is your country not supported in https://pcpartpicker.com/?