Tested on the current ExB Dev Edition Release (1.15 as of posting this)
The tool "Locate" does not have a visible focus within the map.
The tool "fullscreen" creates a keyboard trap.
This tool does not exist in ExB but does in instant app and would be nice to have: A button that explains the keyboard navigation within a map. It explains shortcuts.
WCAG 2.1 AA compliance is federally mandated of all state and local government web content. In order to use ExB, government employees need to be pushing for accessibility enhancements.