Getting started isn't dependent on any particular lab testing - the low-FODMAP diet includes elimination of lactose/fructose/sorbitol, so as you follow your plan you'll figure out if those are triggers for you.
For the things you've already done, you can tell your coach it'll be incorporated into your plan.
The FDA is currently selectively regulating mobile apps, primarily based on risk categorization. We haven't been subject to regulation so far, but will of course work with any regulatory bodies if/when that time comes (and, of course, regulation of digital health products is continuously evolving).
We're building the platform so that it can support any diet, and UC/Crohn's are on our short list. (Some folks with those conditions have benefited from the Low-Fodmap diet too, although it wasn't designed for that purpose.)
Glad you like the idea! Thanks for the feedback about the website. Would love to learn more - is there a particular part that especially falls short (or something that, if included, would have sold you)?