Think about putting the BME680 on the top PCB
The battery is max. 25.5 mm x 27 mm. It will party cover the BME680.
The vent hole of the BME680 is at the bottom and the battery curves up a bit at this point, so the vent hole will likely not be covered, but I don't wont to guarantee that at the moment.
We should think about adding pads for an optional BME680 on the top PCB. We can put it on a different I2C address too.