labels for chart data points

Typically labels are located directly above or to the left of the data. Will that work for you? If so, select the data range including those labels.

The only built-in label options for xy-scatter are x value, y value or Series Name.

If you have a few points you could create a series for each point and display the series name.

The only other way is to use custom text for each data label.
On a PC this can be acheived by using the free addin XY Labeler.
Not sure about the Mac.

The addin allows you to select a range for each point in the series.
Linking custom data labels is indeed a big ommission from ALL version of Excel.

The add basically automates this set of actions.

Select a series
apply data labels
select data labels
select specific data label
in formula bar enter full address of cell containing label, e.g. =Sheet1!A1

The data label should now display contents of cell. Repeat for all data labels.

Some very simple code which does the basic linking would be

Sub LinkDataLabels()

    Dim chtTemp As Chart
    Dim rngLabels As Range
    Dim lngIndex As Long
    
    Set rngLabels = ActiveSheet.Range("C2:C5")
    Set chtTemp = ActiveSheet.ChartObjects(1).Chart
    
    With chtTemp.SeriesCollection(1)
        .HasDataLabels = True
        For lngIndex = 1 To .Points.Count
            .Points(lngIndex).DataLabel.Text = "='" & rngLabels.Parent.Name & "'!" & rngLabels.Cells(lngIndex).Address(, , xlR1C1)
        Next
    End With
    
End Sub