Hi there,
Yes , So it’s the penny wise and pound foolish with this , a swing and a miss IMO. You see from the schematic 
they left us hanging 
the Charge chip ETA9740E8A is also having a 4 LED FUEL Gauge it a LIPO 3A Switching Charger, 2.4A Boost and Fuel Gauge in One ESOP8 with Single Inductor
See , Seeed can always do better 
From the Data sheet HERE
and the Included reference design 2 resistors and 4 LED’s is what’s missing IMO for the absolute Minimum for a display product like this.
Oh’ and 4 tiny holes… 
Curious to get one and crack it open See if just adding a jumper or three 
from the pins on the ESOP8 package to the Xiao socket pins for D6, D7 & D9 “available” …
WoW, someone missed the boat? 
If they were not , they are NOW!
In Rev 2… I would also try a nrf52840 Sense, Low Sleep power, Let the IMU get in on the action, Wake from sleep & gesture controls… NO BUTTONS
Use a Plus variety and Enable an ADD-ON Grove EXTernal Sensor capability , We can do Way better…Add an Interrupt pin for the PMIC
maybe as well.
HTH
GL 
PJ 