In the nano world weight and size is everything. A constant topic is stripping a pi of unnecessary weight and volume. Essentially you can flatten one and reduce the weight of a pi significantly
Interestingly a stripped pi 3b is lighter than a stripped pi 3a+ due to the board thickness.
A stripped pi 3b comes in around 16g
A stock pie zero is around 7g
DISCLAIMER: the hdmi connector is difficult to remove successfully and any of these processes can of course destroy your pi.
Here is a video showing the stripping process