Create a commerce product and add it to cart using Services
Here's a link to the Commerce service's README.txt which includes a bit more detail on what kind of abilities it brings out of the box.


  The following grid indicates what callbacks have been defined so far
  out of the current target set of resources:


Resource         | Index | Retrieve | Create | Update | Delete
-----------------|-------|----------|--------|--------|--------
product-displays |   Y   |    Y     |   -    |   -    |   - 
products         |   N   |    N     |   -    |   -    |   - 
carts            |   N   |    -     |   -    |   -    |   - 
orders           |   N   |    N     |   N    |   N    |   N



  The additional relationships and targeted actions are slated for
  development:
  
  product-displays: products products: add to cart carts: empty, convert
  orders: payments


So then the question is: Can you do what you want with commerce_services?

Can you create a product? Not according to the README

Can you add a product to a cart? Not according to the README