I've spent 9 years Managing service & product-based businesses, I've founded & run 2 start-ups of my own; & Digital Marketing expertise. In my spare time, I volunteer with BUILD- entrepreneurship training for under-privileged youth. Now I'm a software developer for a global software company.
Hmm...this is a loaded question. First, by customer, I am assuming you mean B&M(Brick and Mortar) shop owners. Well I hope you did, because my answer will be geared towards this "customer". Ok- Facebook aside, if I were tackling this question I would ask, "How is the B&M currently attributing in-store sales?" If they are not even tracking it, then why would they be interested in your service? If they are tracking it, but it is independent of the FB ad spend, then a.)what factors do they believe should be attributed to in-store sales, and b.)what was their original goal and purpose for the FB campaign and are they actively evaluating their ad $$? I believe first figuring out what/how each customer is currently tracking it's data, will give you insight on whether or not they have a "demand" to know the FB ad vs. in-store sales correlation. But I will throw a wrench at you, there are numerous articles and research stats/papers out there which speak to the fact that online sale and B&M sales are almost always independent of each other. When tied into an omni-channel approach, this is when you can begin to correlate such independent data sets. However, if the B&Ms are not using omni-channel strategies- then the concept of your application is kinda moot. I believe showing the contribution of FB ad spend versus online sales, would be a more direct approach to your analytics application.
Well first, it's important to point out that this is not a Wordpress site. It's a web application or SaaS. Perhaps it was built with Ruby, Python, or it could be using other JS frameworks/languages. There are many reason why you would not use WP for a site like this, one of those reasons is: Scale. WP sites do not scale well. I would start there. I would research building a web app vs. Wordpress. You will find much insight in regards to scale. This is a great article to introduce you to WP scale and what issues you may run into: https://tommcfarlin.com/scaling-wordpress/
There are several resources which you may find helpful in your search to start a tech career:
1.) LinkedIn- I'm sure you heard this before, but by incorporating key search words into your profile will help recruiters zero-in on you. No experience? That is OK. In your summary mention that your goal is to be an "xx" or "yy". Of course, these titles are job search key words.
2.) Create a profile on AngelList. AngelList gives you great insight on new start up opportunities in your area.
3.) Attend meetups, cohorts, or free events at code schools in your area. Most of these events there are on site staff, or recruiters there actively searching new hires. Also, the majority of these events are held inside of top tech companies, it's a great way to get inside and stalk the company you love!
4.) As far as HR is concerned, you're looking in the wrong place! Most tech hiring decision come from that specific department or department head. Find them! HR is usually the last step in the process.