Now to address your original concern about Bluetooth. Bluetooth is not the best fit but Bamboo printers do have WiFi. They can host local web UI which is what pretty much every other product does. It requires will and resources to support offline tooling for users though. It also reduces the probability that the user will subscribe to their cloud services, if any.
Coming to the point of an App only working at home. Well, there are several ways to address this issue WITHOUT requiring a user to use their Cloud offering. A simple way is to EDUCATE your users that the app will only function on local wifi. Average users are smarter than you think. If the user would like their app to work when they're not home, offer them an option to connect to the cloud but do not make it mandatory. Next, the printer can use a combination of UPnP, Dynamic DNS to expose it over the internet. Yes, it is scary to do this but with the right security practices it is possible to expose your printer over the internet so your app can reach it. You don't need their cloud to be the intermediary.
Finally, these printers will likely stop working entirely if the company goes out of business or decides to wind down their 3D printing business or just plain planned obsolescence of specific models. All in all, subscription & online paid services for hardware products is an anti-consumer model.