Hi there @Augustine_Whitehouse,
Hopefully you'll find solutions here as it seems you're embarking on an exciting and challenging journey!
Feasibility and costing depends very much on the type of application. With regards to feasibility, you would need to provide a little bit more detail about your app's data connections (APIs, databases, etc) and users (will it be a multitenancy app, an app for companies internal teams etc).
Here's another helpful post as someone just recently asked the same thing as you did.
However, if you could provide a little more detail, then I'm sure many people in this forum will be able to provide guidance and tips.