I have been experimenting with the microbit v2 and zephyr.  Everything seems to work ok except for the magnetometer.  The values it produces do not change when you re-orient the device.  If you re-orient the device and power cycle it you will see a new set of values which will remain unchanged until the next power cycle. My build version is zephyr-v2.6.0-535-gbd09d4ff3f81
The accelerometer, bluetooth and digital i/o all work fine.
While wandering through the code and experimenting with various configuration options I came across an error in lis2mdl.c on line 453:
const struct lis2mdl_config *cfg = dev->config;
There is no 'dev' parameter passed to this function however there is a "config" parameter and this modification works: