Can Subpod go underground near fruit trees? Or is it best for it to be in a raised bed?
There is no problem setting up your Subpod in the ground near fruit trees. The tree roots will make really good use of the worm castings produced by your Subpod.
However, please take note that if you stop feeding your Subpod, the tree roots will likely move into the holes of the Subpod below ground. If you use your aerator to stir in your food, you will keep large roots from forming inside the Subpod.
We have one colleague with papaya trees around his in-ground Subpod and they happily grew all around the outside of the Subpod with no problems.