Since POST is an “append” operation, it might be more Englishy to POST to /products, as you’d be appending a new product to the existing list of products.
As long as you’ve standardized on something within your API, I think that’s good enough.
Since REST APIs should be hypertext-driven, the URI is relatively inconsequential anyway. Clients should be pulling URIs from returned documents and using those in subsequent requests; typically applications and people aren’t going to need to guess or visually interpret URIs, since the application will be explicitly instructing clients what resources and URIs are available.