Are you using this large financial application just for yourself?
I think the difficult task is/will be to sell vibe coded software from the lone developer to anyone.
Yes, its for proprietary use among friends; its not for sale, instead I get a cut of their returns for providing support & maintenance.
It is not 100% vibe code, by far not! I use cloud for method-by-method or simple class instructions and integrate in the app manually, I do not use any of the API integrations, I just use the standrad WebUI for discussing, planing & implementation.
Hyper-individualized software is what LLMs are best for IMHO. They lower the bar so much that it's becoming perfectly feasible and reasonable to amase a large amount of software which is fit to your exact personal needs and preferences.