Drag and drop content type and accessibility (keyboard navigation)

We are using the drag-and-drop content type here:

https://uclalibrary.github.io/research-tips/primary-secondary/

and have been trying to figure out if the drag and drop activity type is accessibile from a keyboard navigation perspective.

When we work on the drag and drop challenges, we are able to move one item into a drop-zone using only the keyboard (tab to select and the spacebar to move the item between dropzones) but the second item (as far as we can tell) is not selectable using the tab key.

Very interested in your thoughts and advice on this! Is there a configuration somewhere which would help us make the second item tab selectable?

Thank you!

Doug