Mark, Wow, good question, but my guess is the answer is going to disappoint you. I think the BLE protocol plus the various kinds of data passed between the phone and meter will make this approach very very difficult to extract only the measured values you want.
At this point, I would say the easiest method would be to use Android Studio. James developed the android app using AS. It is free and James provides the source code for each app version for free on GitHub. By the way, this is quite commendable; not every manufacturer will provide the source code for their product apps. It is complex software, but with just a little knowledge and research you can load his latest app source code into the latest Android Studio and it will compile into an app which will run correctly. From there with a lot more knowledge and studying his code, you can modify the source code to do what you want. Not easy by any means, but easier than decoding a serial stream, unless somebody has already done it for you.
Perhaps the Python app would be easier, but I believe I remember reading the latest app is not compatible with the latest meter firmware changes.
As always, just my humble opinion.