HDMI Dummy Plug : ID 4247 : $3.50 : Adafruit Industries, Unique & fun DIY electronics and kits
HDMI Dummy Plug up to 4K — PMD Way
HDMI Dummy Plug 4K High Resolution Virtual Monitor Display Emulator New Generation Headless Display Adapter Compatible with Windows Mac OSX Linux, 3Pack - Newegg.com
False Load HDMI Dummy Plug Virtual Monitor EDID Display Cheat Card with LED MDY-CO457-LED
Is an HDMI dummy plug necessary to run Mac Mini headless? : r/macmini