ok. i found a mount on the internet and a report that it should work. so the gopro should have the same weight and balance as a mobile. because a gopro is apparently lighter. i'll test it and report back. thanks for your feedback.
This could be really difficult because there is no camera winch on the device, and also a gopro might be heavier than a mobile phone, also a GoPro has a different weight distribution. (unfortunately, like any other gimbal, the Dji osmo needs to be balanced before use).
I haven't tried it yet, but I would leave it alone.