I'm prototyping a USB port protector for my P10 because I want to protect against accidental yanks which could damage the port.
The TRS 1/4" inputs on the back are secured with washers, so this is sort of the same idea.
The protector fits snug, and does not need any magnets, but I can add that. And I found that there are two types of sizes for the end of USB cables, one pretty standard, and another for chunky ones.