react-native init in current folder

This issue is currently tracked there.

The reason I wanted to do this was to have a sort of mono-repo, but I have transitioned away from this approach as I am not sure it is beneficial.

You should have install react-native-cli instead of react-native globally as described here.

And then the command is:

npx react-native-cli init appname --directory ./appPathToDir

You can do

$ cd .. && react-native init folder_name

It will overwrite your package.json but keep the non-default files.