In the Rules of ARIA attribute usage by HTML element , <button> already allows every child role of composite widgets that manage focus except for tree and grid.

There are benefits in using <button> as a base of interaction in these widgets, such as:

• Enter/space triggers the click event
• Certain colors and interaction styles are applied automatically in forced color modes like Windows High Contrast Mode.

Those benefits also apply to gridcells and treeitems, so it seems like it would be valuable to add those as well.

Happy to do a PR for this :)