Most of the pages on your site are of extremely poor quality and provide little to no content to users at all. Google cares about user experience and their mechanisms can easily detect poor quality content.
They basically said, "we can stop here because this is ongoing we can't index 1 million generic probably automated pages". Your product pages already exist and are indexed and match other pages on the web, they simply choose not to disply in their index because other better quality content already exists and your pages are below the threshold of even being considered good enough for anyone to read or interact with and that is why most of them don't show up. They hate little or no original content and probably consider the fact that you scrape content. This means that your site has red flags all over and is sort of blacklisted. Which means it will take a lot of hard work to start getting pages even of good quality content indexed.
Being the fact that your pages only contain a product tittle that matches another website with the same information but their sites is of quality, they simply consider your website as a duplicate content website or a scraper and they don't index or work with scrapers.
Product pages normally include descriptions and yours, not even that. They are getting smarter and smarter every day..
Although Google indexes billions of webpages and are constantly
working to increase the number of pages they include, they don't
guarantee that they'll crawl all of the pages of a particular site.
Google doesn't crawl all the pages on the web, and they don't index
all the pages they crawl. It's perfectly normal for not all the pages
on your site to be indexed.
In my opinion you have quite a good average of pages index by their
While they can't guarantee that all pages of a site will consistently
appear in in their index, they offer guidelines for maintaining a
Google-friendly site. Check the following:
I would suggest as @Martijn said. Work on your pages, develop their credibility, stop generating or creating those types of pages. Make your site look authentic and give authority to in every page with quality genuine and original content. And that is the basics that you need to do in order to get your pages indexed. Right now it simply looks like a site that scrapes pages. User experience is a priority for Google and your site does not offer any good on that in those pages.