"Each rechargeable battery holds 5-8 flights using the default flight modes." [1]

[1] https://pixy.com/shop

I believe each default flight time would be measured in seconds, so it's understandable that they are recommending their "Dual Battery Charger" (Two Pixy rechargeable batteries with USB-C charging station).

They appear to have deliberately made the batteries as easy as possible to swap out, for this reason (based on the second half of the Learn - "How to Charge your Pixy" video: https://videos.ctfassets.net/svn43w404u4n/6RMiSJPQrtPdQdCoO5... )

EDIT: See also - https://news.ycombinator.com/item?id=31195565

From their FCC application:

Battery: 3.85V DC, 860mAh, 3.311Wh

https://fccid.io/2AIRN-006/RF-Exposure-Info/220100298SHA-004...

Cool site by the way; FCC listings are always so hard to search