Creating a remote keyboard on a mobile device that connects to unity...

So, not even sure where to start, im working on a platform with limited internet, NO play services or anything like that, and often just local wifi.. What I would like to do is create a qr code (or even just give them a link) for each player that would pull up a interface hosted by a unity http server?!? where players could input text into their interface on their phone, and the unity app would be able to retrieve that text.. basically, 4-8 people using phones as remote keyboard entry controllers... any thoughts or ideas on where i can even start with this idea?! gotten myself lost in searches, and not finding what I want..