That sounds good! I will follow this up accordingly.
I can understand that the app list should not become confusing. However, in order to be able to control the system apps individually, I still think it is necessary to list them all separately. This could be solved by displaying the system apps in a separate list. You either look at the list with the clearly arranged user apps or the list with the system apps. You could perhaps use a switch to toggle between user apps and system apps. Maybe that would be a viable solution?
(By user apps I mean all apps that are displayed in the Android settings under Apps->All Apps. By system apps I mean the ones that are only visible there when you enable “Show system apps”).
That’s basically what I meant. 
You would just have to additionally make a switch “Block network access on/off” in the options.
If “Block network access off” is selected, the black list mode is active and only the apps that are checked under wifi, mobile data, vpn are blocked for the Internet.
If “Block network access on” is selected, the white list mode is active and only the apps that are checked under wifi, mobile data, vpn are allowed to access the Internet. Alternatively, no app can be checked in this mode and only individual domains (for example, via the existing “stream” item) are allowed to access the Internet.