We are running into this blocking issue auth0/Lock.Android#188. As I'm researching a fix for that issue, I notice you deprecated the whole react-native-lock library in favor of the 'getting started' approach.
The getting started guide basically advices using .webAuth and opening Lock in a browser, which I consider a downgrade in usability and perceived security, compared to native login screens. So my next option would be to look at the platform specific Lock at https://github.com/auth0/Lock.Android and https://auth0.com/docs/libraries/lock-ios/v2. I feel hesitant to proceed, as this is basically what the react-native-lock package did for us and I don't know if those native locks will be supported in the long term or deprecated just like react-native-lock? Also, they add a lot of platform specific complexity to our project.
My next step is to (unfortunately) roll our own against your API's, rendering a minimal login screen directly in React Native.
I understand that supporting SDK's for all the various platforms is a moving target for you, but will you please consider creating a proper JS based react-native-lock version?
Considering React Native is so close to web, this could be a simple port of the web version (also in React). I'm more than willing to help out on this if you (Auth0) want to commit to supporting it long term. It would help making Auth0 the de-facto standard authentication option for RN developers.