I am interested in this project. I have quite a bit of experience with the PI from previous jobs. I have never used bluetooth on it, but I'm familiar with the protocol. I have also worked on some fairly large systems so I think I'd be able to draw you out a scalable and maintainable design.
There are some things that are unclear to me about the project:
a. Do you already have any code on the PI? If so, can you give some info about this. If not, I'd use raspbian as a base.
b. I'm assuming you already have another component that interfaces to the user which takes the Wi-Fi config. Do you already have an API for its bluetooth communication? If not, then we could just send the wpa_supplicant file over bluetooth and use inotify on the PI to connect when the file changes.
c. The bluetooth sensors you mention, do you already have an API for retrieving their data? This is important because I'll have to emulate their behavior or have access to them.
d. How strict is your requirement for VS 2019? All of my PI development has been on linux, so I'd rather waive that requirement but I'd be willing to work with it if it's a must. In either case, I'd give you code buildable with cmake so you could set up your own windows project and use it there.
So, the exact deliverables depend on the above. If I was to make assumptions, the deliverables would be: a debian package for the functionality, a tarball with source + build script, and a doc (architecture, API, usage)