Can I do this with WordPress?

Hello all,

I have a theoretical question I was hoping someone could answer for me.

I will soon be starting work on a WordPress site for a friend who is setting up a brick-and-mortar store. For now, the website only needs to be informational/blog-oriented, but later on, she would like to add an “order pickup” functionality to the site (whereby customers could browse the site and mark certain items for pickup in the store later that day. Sort of like a “pre-order” or “put aside” functionality).

My question is: will building the site in WordPress affect her ability to later integrate the order pickup functionality? Or in other words, does building a site in WordPress affect your ability to integrate special programming into the site later?

Thanks!