Are you familiar with Loop? I believe they are currently just intercepting the Dexcom notifications rather than connecting directly over BLE by default for the G6/G7. However the xDrip + xDrip4iOS projects have gotten the G5/G6 BLE protocol to a state of being fairly well understood.
Out of curiosity, why do that? The Dexcom app already has the ability to generate detailed logs that you can just email to yourself. It’s actually a very handy feature.
There is an entire open-source ecosystem around having direct access to your diabetes data, which predates the commercial availability of things like sharing glucose data live with others. The Nightscout Foundation (https://en.wikipedia.org/wiki/Nightscout) and Tidepool (https://www.tidepool.org/about) are two nonprofit organizations who lead development on open-source products (Nightscout and Tidepool, respectively) which help with this.
While the manufacturer-provided ecosystems function okay, they give you limited data mobility in case you switched to a different diabetes-related product like a CGM or insulin pump. They also introduce a dependency on on a cloud SaaS platform managed by said manufacturer, which can impose limitations, such as not allowing for real-time access to your data (Dexcom requires an approval process to get real-time data from their API: https://www.dexcom.com/webapi) and can have uncertain reliability (Dexcom had a notable outage in 2019, for instance: https://www.wsj.com/articles/diabetes-blood-sugar-data-outag...).
Conversely, you can run a Nightscout server on a Raspberry Pi in your home, or on a cloud server, for yourself and have full access to your data.
I’m familiar with tidepool and nightscout etc., I’m asking about using that functionality with a modern Dexcom device and app.
It is categorically untrue that you have to enable the cloud option to store/create logs and reports with the G6/G7. The app creates fantastic and easily digestible logs/reports on your phone, without any cloud processing.
I did a proof of concept with a Bluetooth scales so this should work. I'll add a README after work:
https://github.com/BrianHenryIE/tweakdexcomg6