Thank you Dr. Dave for answering this question. It's disappointing this won't be accessible any time soon, but it's good to know.
A bit of news from ALiveCor: https://techcrunch.com/2018/09/11/alivecor-gets-a-green-light-from-fda-to-screen-for-dangerously-high-potassium-levels-in-the-blood/
So maybe it will be seen sooner than expected.
Nov 18th 2018
If you are still looking for a home testing kit for potassium I have just found one called “Vitastiq”. It is available at Harvey Norman shops in Australia. It measures 26 different vitamins and minerals in your system. It does not give actual readings but measures whether you are low, normal or high and it actually works. Very simple to use through an app on your phone.
Many thanks to Gary, Dr. Priya, and Dr. Albert for the updates. Sounds like the Laqua Twin is still the best option on the market at the moment, which is valuable to know.