Just call people by phone and read off some numbers from paper. Then confirm them by reading them the other way round. Yes, it is actually that easy!!! People have transmitted vote counts this way forever, long before apps were a thing.
You can even use your goddamn smartphone to make the call, if you need that in order to feel "modern" enough. But don't make a shitty app for every one-time event that doesn't need a hundred additional failure modes for essentially no benefit whatsoever.
You can even use your goddamn smartphone to make the call, if you need that in order to feel "modern" enough. But don't make a shitty app for every one-time event that doesn't need a hundred additional failure modes for essentially no benefit whatsoever.