You could also move most of what you do to a tablet or laptop if you’re willing to carry that, and just use the phone as an Internet access device and for phone calls.
EDIT: Or use a cell modem for data and SIP service for phone service and texts, though then you need to have a device that you’ll keep on if you want to get incoming calls when they come in. Cell phones are pretty optimized for low idle power usage.
There are phones that run on other platforms, but the app library and hardware isn’t competitive.
https://en.wikipedia.org/wiki/List_of_open-source_mobile_phones
You could also move most of what you do to a tablet or laptop if you’re willing to carry that, and just use the phone as an Internet access device and for phone calls.
EDIT: Or use a cell modem for data and SIP service for phone service and texts, though then you need to have a device that you’ll keep on if you want to get incoming calls when they come in. Cell phones are pretty optimized for low idle power usage.