One idea for Supermetrics for Google Sheets -- An option where you can have the metric or dimension definition (from the API) be added as a note in the cell where the heading is. 

Very often I forget exactly what a specific metric is measuring, especially in the era of lots of metrics changing in Meta. To have quick access or notes right there with the data would be great. I do know the definition is there when you are setting up a query and hover over the metric name in the sidebar, but that’s only when editing a query.