I meant that I had flashed the image onto the sd card in the pi. And by "hang", I meant that that nothing happened after that. It is now working for some reason. Not sure what I did.. The wifi goes into monitor mode etc etc. Thank you anyway, for being kind enough to reply.

I've tried mounting the images at https://build.nethunter.com/nexmon-pi-builds, but they hang. Could it be that my Pi 0 W is a later version than what these were tested on? Mine has the wifi built into the board. Thanks