Virtual machines also exist. I once got bit by a proxmox upgrade, so I built a proxmox vm on that proxmox host, mirroring my physical setup, that ran a debian vm inside of the paravirtualized proxmox instance. They were set to canary upgrade a day before my bare-metal host. If the canary debian vm didn’t ping back to my update script, the script would exit and email me letting me know that something was about to break in the real upgrade process. Since then, even though I’m no longer using proxmox, basically all my infrastructure mirrors the same philosophy. All of my containers/pods/workflows canary build and test themselves before upgrading the real ones I use in my homelab “production”. You don’t always need a second physical copy of hardware to have an appropriate testing/canary system.