I've tried all day to get this working and I've been unsuccessful so far. I managed to find a Lineage OS Nougat ROM for Nexus 5, I have the Nexmon firmware copied into the correct place, I have root, chroot and the nethunter 2020.3 you linked above and I can't get monitor mode to work.

On my most recent effort I have finally got the ". monstart-nh" and ". monstop-nh" commands to work insomuch as they are accepted by the terminal, but it doesn't appear to actually be enabling monitor mode. Previously I couldn't even get the command to be recognised so I suppose that's progress at least.

After starting monitor mode and trying wifite, it can't see any interfaces in monitor mode. Am I forgetting something crucial and obvious here?