I don’t know much about batteries but seeing as many people seem to have reported around 8-10 hours of battery life on the Framework, I wonder if it’s possible to upgrade to better batteries.
Battery technology is improving all the time. So before long I suspect it will be possible to build an identically sized battery with greater capacity.
So at some point in the future, I suspect it will be possible for Framework to offer higher capacity batteries of the same size that fit 1st-generation Framework chassies/mainboards.
Given their commitment to upgradeability, I suspect it is something they would want to do.
When that would be though, I have no idea.