Hi Jonathan, welcome to planDisney!
You bring up an excellent question, and I'm glad to help!
Just like you mentioned, selfie sticks (hand-held extension poles for cameras and mobile devices) are on the
list of non-permittable items at Disneyland Park and Disney California Adventure Park. But I do want to mention that folding tripod stands that can fit inside a standard backpack are actually permitted!
And on to your main question, I have good news! Gimbal stabilizers are allowed if they do not extend. If they do extend, then they could fall under the category of "hand-held extension poles for cameras and mobile devices" and could potentially not be allowed in the parks. So as long as your gimbal stabilizer does not extend, you should be good to go!
And speaking of pictures, did you know that you get unlimited
Disney PhotoPass Digital Downloads with the purchase of the
Disney Genie+ service? Definitely something to consider if you haven't yet!
See ya real soon!
Jin