Website Design – Display categories on both the homepage and category page?

I'm creating a "Directory" website that has many pages, each belonging to a category and a subcategory.

I have category pages that list all the pages belonging to the categories.

Example:

example.com/categories/blue-widgets/

Will display all blue widgets (100 items – each linked to a specific page)

example.com/categories/blue-widgets/blue-mixed-with-red/

Show all blues mixed with red widgets (similarly, 20 items).

It's supposed to be good for SEO too, to make the first level accessible to the robot too.

But under this logic, I must also do example.com/categories/ accessible, and I do not want to show all 1000 articles of this page because it's too much, and not useful for users.

So, I thought I might only display categories and subcategories on this page, but that's exactly what I plan to do on the homepage. So I think it would be wise and wrong to make this type of duplication a bad SEO.

If I do a 302 redirect from categories on the homepage, which does not feel good too.

So, what is your suggestion, wise SEO / Content / UX? It is important to note that my main concern about this page is more in the perspective of SEO.