I made a charging cradle for Garmin Edge 530, 830, 1030, and 1030 Plus computers that uses the Charge Power Pack contacts on the bottom of the computer.

It requires extra parts- pogo pins, wire, and a USB C breakout board and you have to print it yourself. If there's enough demand, I'll iterate the Shapeways design so the pogo pins fit better, but you'd still need to get the other parts from DigiKey and solder them yourself.

There are some drawbacks (low charging speed, possibility of short circuit if you do something stupid, error messages because it thinks an external battery got disconnected, not for use while riding, and others, I'm sure), but it's so nice not having to open the charge port door and plug in a micro USB cable- just snap the computer onto the cradle with just one hand.