See end of this thread: Sony Smart Watch 3 and iPhone in Tandem (simultaneous connection) - #51 by docslotnick
It seems Dexcom App on iPhone and xDrip+ on Android will not work concurrently, but will work if you disable Bluetooth on one of the devices. I’m interested in using xDrip+ SW3 smartwatch as standalone, but only during runs, switching back to iPhone when not running. I haven’t tried this yet, but it would be convenient just to get BGs on standalone watch during exercise (and know when I potentially go low and require a carb) and not have to carry iPhone and RL since I typically use a ZB during exercise anyway.