Perhaps there are other bluetooth intervalometer devices available...
I use the MIOPS smart as an intervalometer, it has bluetooth connectivity
The device can also trigger the cameras based on light, sound, laser, or other sensors that may be connected to it
MIOPS Battery life for me has been great, but note that the coldest I have used it is about 5°C
A disadvantage may be the cost, about $200 dollars, more expensive than just an intervalometer