I had one I put together about a year ago that sends MQTT to my system to be logged. Then I got bored because the reading NEVER REALLY CHANGED (Thank goodness!). I actually powered it back up last weekend and verified it worked, but I think it'll have to look prettier to justify its existence.
I jut took a cheapie kit from Electronics Goldmine, removed the LED and swapped in an optoisolator. Easy peasy input signal to an ESP32. Unfortunately it's a pretty slow opto, so I cant detect pulses that are too close or fast, but it's not really about accuracy I guess...