Interestingly, a version of this technology was built by a government contractor some years ago, because they too wanted to track people indoors. I don't think it used a smartphone though...

I think an acquisition would be unfortunate. This could become really huge / useful to the world without being locked up as a private company's IP. Personally I would license it rather than sell it, as well as offering offline apps and limited SaaS. You don't need an established enterprise to sell it commercially; you just need a sexy product and some industry vets with contacts. If you do end up going that way, and need someone in IT Ops / DevOps / SysEng stuff to work on the "going enterprise with a billion users", give me a shout.