already about the demo code: in short, .getProduct() does not exist.
I made a new project of my own, added Wix Stores, same problem: the generated Stores product is also called $w("ProductPage1), but all the events like .getProduct, and the ones beginning with .StoreProduct are not available, they do not show up in the dropdown list after you type $w("ProductPage1).
Also, the demo version of your code on https://www.wix.com/code-examples/shop-related-item/product-page/pom-pom-lip-balm
does not show any related products for me, but in browser console I DO see a lot of "Permission denied" messages.
Does one need some special license to be able to use this? If so, how do I get it?