Build links to authority site

My clients have a website, which is similar to alibaba (just a question)
Example: https://wholesaler.alibaba.com/w/ch-a.html

if they want to boost up the 1+ millions product pages (Example: https://wholesaler.alibaba.com/w/wholesale-a0.html)

Where should we build links to? as we can't build links to all 1+ millions product pages (too much..)

should we build links to https://wholesaler.alibaba.com/w/ ?
or should we build links to https://wholesaler.alibaba.com/w/ch-a.html ?
or should we make random internal links in products pages and build specific product pages?

or any suggestion?

I would create a silo structure where your product pages link to a major pillar post in that category targeting keywords. Have a long pillar post on the homepage for main keywords, link to major categories via pages created for those categories. Link from categories to product posts.

Best 3 blogs for building an authority site is:
RankXL
FatStacksBlog
Authority Hackers

I can't create long post in homepage as their page is similar to alibaba which is authority site.
Any other suggestions?

The pillar posts don't have to be posted in their entirety on the homepage, they could just be linked to.

search this in google, site:sitename.com keyword

then check which page is ranking and start working on that page.