You're thinking too small: updating is just one specific thing that remote monitoring and managing software can do. There is lots of choice in the GNU/Linux ecosystem, and since it is based on Debian, probably all of them can be applied to Proxmox. Just use the one that you like most as a (many) systems administrator.
EDIT: I use Ansible to (install ansible and) update all my VMs and Proxmox, for example. It could be used to query stuff but I would have to script it myself.