This is looking so great. I'm also working on the same project for my automatic skate running. You can read here the review of skateboard https://skateboardslife.com

hmm looks like you probably need to have a powered axis that the trucks pivot on  as well, this would be great because you could increase rideability by altering the max steering angle in relation to velocity, would really take the wobbly factor out, you will need to build a model to calculate the ideal angle limit curve, probably could do this by finding your CG and figure out angular momentum needed to move CG over centerline of the board to overcome forces applied while turning. its a great start though, and probably way easier than a CV solution

Now it's harder.  In the future it could be easier.  Balancing yourself on a skateboard with a thumb operated joystick is challenging but doable.  I have plans to strap a Vive lighthouse on the skateboard and implement a closed loop control.  Either you wear a tracker on your body or hold a tracker in your hand.  The control loop would try to keep the skateboard under the tracker and may include an offset from another comand source, for example a joystick.  A tracker on a stick would probably work well.

Would you say it's easier or harder to ride than normal skateboard?

Now it's harder.  In the future it could be easier.  Balancing yourself on a skateboard with a thumb operated joystick is challenging but doable.  I have plans to strap a Vive lighthouse on the skateboard and implement a closed loop control.  Either you wear a tracker on your body or hold a tracker in your hand.  The control loop would try to keep the skateboard under the tracker and may include an offset from another comand source, for example a joystick.  A tracker on a stick would probably work well.

Computer vision would also work well.  Probably better.  I would start with camera mounted on the skateboard looking up.  The driver would hold a visual target in their hand.  The control loop would try to keep the skateboard under the visual target.  In that same way you could make the skateboard follow things like your bicycle, other skateboards, ect.

Hmm, following bike - good idea for a "dog skateboard for transporting your groceries", but it would be probably too prone to tipping. But if it was a little wider platform... Overall, nice idea for steering!