Here's an easy solution for keeping your micro HDMI ports free from dust and other unsavory particulates. These squishy Silicone Micro HDMI Dust Cover Inserts slip neatly into any computer or device with an HDMI socket, like the Raspberry Pi 4. 

Comes in a pack of ten, so you're set even if you have a display or computer with a lot of micro HDMI ports, or if you lose some. Micro HDMI is a rarer type so they are more expensive

We also have these covers for standard HDMI, USB A, USB C, and RJ-45/Ethernet ports.