" The reason for the cost constraint is that this is a
" The reason for the cost constraint is that this is a prototype project that could possibly be mass manufactured in the future. "
Sorry but as a designer that has been down that road many many many times you've lead with a common misconception. First you get it working, demo it and then cost reduce it.
If you lead off with cost, you've lost almost any chance of demonstrating your concept to obtain the next round of funding for the cost reduction phase.
Since I know so little of your project I am left to write about lessons I've learned over the years.
--> What is this issue with wasting 20 to 30 bucks to get to mass production?
I've seen that happen as well.
Have you thought of a Raspberry Pi stick for the I/O (25 bucks) and then for the wifi, some router till you get the Raspberry Pi WiFi working?
--> How much embedded design have you done? I started in the late 70's so I have worked on most systems over the years.
I know you may not want to tell enough to reveal what's up but I can assure you that most things have been done and the idea of an IP control link page to control hardware is well, very well done. I think the first time I did that was early 90's. Later we moved to using a web browser.