You don't need a robot arm, just mimic a usb keyboard.

https://pikvm.org/ and similar exist.

This is maybe not as good as the article solution, because it requires you to secure the pi too.

An equivalent, but simpler, solution would be to use a network-based KVM, like PiKVM. You connect a USB connector to the PiKVM so it can simulate a keyboard (and mouse), an HDMI connector so it can show you what’s on the server screen, and you also connect a special cable to the server motherboard power and reset pins, so the PiKVM can “press” those buttons remotely as well.