We remove two batteries for UNLIMITED POWAHHH!*
In terms of actual power, the larger of the two batteries is limited to a typical capacity of 2370 mAh and 9.15 Wh, with the smaller battery sporting 930 mAh and 3.59 Wh. All that adds up to 12.74 Wh.
Stubborn glue secures both batteries, per usual. Alcohol and careful prying are required to fetch them out. This is starting to look like a miniature Galaxy Fold...