Hello OP thanks for giving me some motivation, I myself am busy building an App Development company. I'll be building apps similar to what you (or your friend's website) are selling. My apps will in fact only be native apps.
To all those doubting this I have long believed that their are a lot of potential in selling apps to businesses (do a quick google search for usage of apps and mobile phones). If you were a club or a restaurant owner how many customers do you need to get through an app just to make your money back? And if your service is good enough you could even turn those customers into repeat customers, who then tell their friends... It can cause a viral effect.
The problem however lies in educating business owners about apps...
I do however agree that the quality of apps your website delivers will not be of the utmost standard but most business owner are not very technical. If the app can receive push notifications and customers can get contact details through the app it's enough imo.
Good luck to all.