seo – Hierarchical vs Flat sitemap

Your question is divided into two categories, each with different considerations:

XML Sitemap
In your XML sitemap, you can specify both the frequency of change and the ranking of priorities for different pages. This helps search engines determine the importance of a page on the site and the frequency with which it must be searched for changes. Avoid listing duplicate content pages such as / fashion / women / shoes and / fashion / shoes / women. In this case, choose the canonical URL to submit to the search engines.

URL structure
Respecting a minimum hierarchy in your URL structure for each page or faceted search results will allow a search engine to index your site and view top-level category pages. (For example, the result of searching a department store may indicate different departments).

User experience
A menu too deep can hinder the user experience, which might be overwhelmed by choices or simply tired of exploring many levels of navigation. Having a good faceted search interface with the most common categories as predefined filters can help avoid a too complex menu. In the same way, having an Ariane thread on the page can help users to return to the top-level category or sub-category pages.

Search Engjne Optimization for the products themselves
For each product on your site, consider adding schema microdata in your markup. This will help search engines identify the individual products available for sale on your e-comm site. See https://schema.org/Product

Also remember to add an RSS or XML feed and submit it to several sources to improve the reputation of your site.