I built a test app with one of the services to see how the basics worked. When I get a chance next week before going live, I'll give it a test to see if the checkout works from within the app. It should, the only thing is will it report back to the main store without being integrated through the API's.
I sell fishing tackle and from experience with Playstore, I know there are a ton of folks that download apps from this niche, even if it's just to see how they work. How cool it would be for a fisherman to be able to order tackle from their boat
***UPDATE***
Site changes such as products added and inventory changes are pushed to the app
Bad news is, ran a test order using guest checkout and check as payment and it did not report the order back to the main online site
First test, first service. Overall I'm encouraged so far by the results. So the answer to an app is, yes it can be done and the reporting back to the main site shouldn't be that difficult integrate.
Will keep you posted on progress. I will figure out a way to implement a sucessful app. To many sales dollars riding on it considering the number of people that use mobile as their only source of online access.