Android Nougat - Network Security Configuration for Charles Proxy
If you want to to look at the network traffic there is still the possibility on a rooted device to use XPosed and one of the Anti-SSL modules (e.g. JustTrustMe).

Unfortunately XPosed is currently only available for 32bit Android versions and most Nougat devices I have seen use Android 64bit. 

Or if you want to investigate a regular app from AppStore you can modify and re-sign the app (e.g. via APKTool) - of course this only works for apps that don't have an integrity check.