I appreciate you for reconfirming this with us, sychan.

Base on the procedure laid out, you're doing it right. Furthermore, when your supplier changes the product price, updating the price of your Purchase Order (PO) is optional since it's a non-posting transaction. You'll want to enter the new price directly on the bill or other expense transactions.

Here's an article for available reports that will help you see the product cost, the product on hand, and more: Use reports to see your sales and inventory status.

Also, you are correct when you say COGS automatically calculates once you issue an invoice or sales memo. Learn more about how QBO calculates COGS through this article: Cost of goods sold: How to calculate and record COGS.

To give more information about managing inventory in QuickBooks Online, check out this article: Inventory management.

I'll be right here if you have further questions. Keep safe and have a good one.