promote your product with seo friendly titles and easily searchable goods. then only they can be easily found on the google product search results.
Do SEO. If you have your own website for your products, do link building or backlinks. This will add traffic to your site then Google will be able to recognize your site and your products.
ensure you have met all the requirement and OPTIONS in the product feed spec - GTINs are vital - then you are just competing on price and reviews!
Aside from the long list of suggestions made by the members here, you may want to post your website's URL so we can all have a slice of it. I mean, we could check what's working and what's not. You may also include your list of keywords and their current rank.