[jech]

It's also possible in LineageOS and its derivatives.

But it's not very useful in practice: if an application doesn't need networking for its core functionality, then there usually is an open-source equivalent that does not use the network in the first place. The few applications that lack a good open-source equivalent (public transportation, proprietary messaging protocols, banking) don't do anything useful without network access.

[upboundspiral]

Being able to block network access gives me peace of mind regardless if the app is proprietary or open source. Humans are fallible and life can get in the way (maybe the app has old dependecies with vulnerabilities, or any other random thing that I don't want). Being able to set the permissions I want only has upsides.

[jech]

Oh, fully agreed.

What would be more useful, however, would be the ability to selectively block network connections: for example, to allow the public transportation app to access its API endpoint, but not the advertising and tracking endpoints. I don't think LineageOS allows that, and I don't know if Graphene does.