Can I show "only 5 left" or a stock count on the product page?

Yes. Go to Inventory → Inventory Settings and, under Storefront display, tick Display stock details on the product page. Then choose:

• Placement (hook): for example After price, Before Add to Cart or End of product summary.
• Design: Text (green), Pill badge, Bar with dot or Bordered box. A live Preview is shown.
• Format: the wording, where %%count%% becomes the quantity. For example, Only %%count%% left.

Click Save Settings. The count uses your Inventory stock when the product is managed there, otherwise the product's own quantity. It only shows for in-stock products that track quantity. Out-of-stock items show the usual out-of-stock state instead.