Is there a way to see how many of a certain inventory item / all items you have sold (in number and in value)?
this will help me checking which items/products are getting sold in a period of time.
Have you seen Inventory Profit Margin report? It shows profitability per each inventory item for the specified period. If you need to know sold quantity, then that is being shown in Inventory Quantity Movement report.
Feel free to propose new report layout but these two reports can give you figures you are after.