Index.php query based on pretty URL?

Hey guys,

I have pretty permalinks set up on my site, so that a post that fits under the “deals” type (which is part of a custom taxonomy, not a wp “category”) will have an address such as:

https://www.site.com/deals/post-title

What I want to do is make it possible for users to enter “https://www.site.com/deals/” as their URL, and be presented with the regular index.php, except that content is filtered to only display the “deals” posts.

I know I can do this by setting up a page specifically for that URL and having a specific query that only looks for deals… but I’d rather it all be done via the index page, so that I don’t have to set up a custom page for each different type of content.

So my question is: how can I tell the wpquery on index.php to filter results based on whether the URL (“https://www.site.com/”) has an additional segment on the end, such as “deals/”?

I’m familiar with passing php variables in URLs by using the “?” symbol, but in this case I want my URLs to maintain their “pretty” appearance.

Any help is much appreciated!

Thanks in advance,
Hadyn