How to Use an iMac as a Monitor for Headless Devices

Headless devices are everywhere now. Mac minis, Raspberry Pis, Linux systems, mini PCs, cameras, and embedded devices often run perfectly fine without a dedicated monitor attached — until you suddenly need direct access to the screen. That is especially true during setup, debugging, recovery, or when remote access is not available yet. https://medium.com/@chris.ahrweiler/how-to-use-an-imac-as-a-monitor-for-headless-devices-9de25f519fb4