I've seen this come up a few times, especially in Shopify forums.
It's not Google's responsibility to index your store.
You need to have content that is good enough for Google to want to index it.
They want to index everything but if you have no content, content copied from your vendor, or boring content then the page will be given less priority. With large catalogs that means pages might not ever be indexed by Google.
It's much better from an SEO perspective to have one product with great content than 10 pages with no content at all. But it's also better to have one page with great content and 10 pages with good-enough content.
It's a content marathon, but one you have to take responsibility for.
One SEO feature that actually works is structured data.
Mostly because the data helps Google's algorithm which makes their job easier.
You can either audit, code, and test your store's structured data by hand or install JSON-LD for SEO and have the structured data you need for several types of Rich Results.
It's already helped a few thousand Shopify stores with their structured data and it could help you too.