I am not sure if this is new, it may be from the late 2018 Google change but Google can now let you see all the products within a collection when Google shows a products carousel in the knowledge panel. This also may be more prominent now with the product enhancements in search from a few weeks ago.

Clarie Carlile posted on Twitter that you can now see below the product carousel within a knowledge panel a link to “explore collections” for a specific e-commerce category. Here is a screen shot that I can replicate on Safari on a Mac but not Chrome on a Mac:

When you click on the explore link, it opens up all the products in that category from that site:

This might be a limited test because not everyone can replicate it all the time.

Forum discussion at Twitter.