google sheets data validation custom formula filter
-- Google Sheets: Using filter() -- in custom formula in data validation =query(filter('sheet1'!$A$2:$A, 'sheet1'$A$2:$A < 4), "select Col1 where Col1 = '" & 'sheet2'!A2 & "'") = 'sheet2'!A2 -- Note: The 'sheet2'!A2 must be -- the first (top-left) cell of the validated range