You're good. The upper limit is 100Wh. Watts = volts x amps.
Inside the 26800+ is 3.7V cells so 26800x3.7=99160mWh or less than 100Wh.
The Wh is written on the battery if they want to check. It probably says something like 98Wh or close to that.
Must be carry on not checked as it's small enough to be extinguished by cabin crew if it begins to fire. Which is why allowed.