Possible to only display results that match search query?

I was working on a directory listing, split by groups that list all names that start with the same letter.

The way I know I can do it is to add every post to a new Category named with its starting letter, and then include that category in the [display-posts] tag. But that also means I have to add 26 new categories, which can be a bit messy.

Is there a way to instead to have the plugin only display posts that start with a specific letter?

I was hoping to have something like this:
[display-posts category=”people” titlesearch=”A?”]
[display-posts category=”people” titlesearch=”B?”]
…

Instead of creating 26 new categories and doing something like this:
[display-posts category=”people-A”]
[display-posts category=”people-B”]
…