I have been spending some time adapting Bangle applications to the SMAQ3. You can see some of the results in the pictures below.
The flash memory, magnetometer, barometer and touch now all work reliably and reasonably efficiently thanks to Gordon's work to which I have contributed a few bug fixes. The heart monitor VC31 chip remains a mystery.
Once you do the initial flash of the watch using the SWD interface, subsequent firmware updates can now be done using bluetooth which is a great convenience as the DFU loader for the NRF52840 seems to be much faster than that used for Espruino on NRF52832 devices.
When compared with the Bangle, the always on reflective display is great in daylight, but at night, the backlight tends to wash out colours and the Bangle display looks much crisper.
Battery life is nowhere near as good as the Bangle - I get 4 days and I am sure this can be improved, however, the battery at 175mah is smaller than the Bangle.js battery. It is also worth mentioning that the charging cable attaches very insecurely due to having 4 pogo style pins rather than only two on the Bangle. In fact overall, the SMA Q3 is a much less robust watch than the Bangle.
The GPS works OK, however, it loses signal in places where the Bangle does not - I think the Bangle has a much better antenna.
You can see the adapted SMA Q3 apps here together with a version of the firmware necessary to run them.
Some Bangle Apps will run without modification on the SMA Q3, especially using the standard Espruino build for the SMA Q3 which has simulated buttons. However, most apps need to be modified to deals with the different screen size and limited colour palette and to take full advantage of the touch interface.
Lastly, the additional RAM on the NRF52840 is liberating - you can run as many widgets as you want:)
Some pictures of apps running on the SMAQ3:
Multiclock App - Clock face
Multiclock App - BMP280 face
GPS Recorder App - Menu
GPS Recorder App - Track display
Note that the red padlock icon means that the screen is locked i.e. touch disabled. On the Bangle this would be display off, however, with an always on display, we simply disable touch to save power. Enabling is controlled by the usual LCD Power On settings e.g. button press.