Q. Power and storage consumption

I thought the data event from the GPS would wake up the pico if it was over 1.5 seconds. From what you've said I'll need to make sure the pico is awake on time. In that case and considering what you've said about power I might leave using sleep for a v2 of this. I'm not seeing how I can use a setWatch for the serial data.

I would be worried about rounding errors in the timers, what's the resolution to the clock? I know IE was famous for only going down to 15.6ms