So their explanation is "Sensors and Network enabled by default to avoid making using the OS harder to use than Android for new users because apps would be broken without them with users not knowing why, although we do make a notification about Sensors access when it's disabled which we can't do for Network."
So if GrapheneOS does let you know when sensors are needed if you run an app that requires then after disabling, and given that 95%+ of apps don't need them, I still can't understand the logic, but alas, not much I can do about it.... I disabled for all future apps when I first set it up, then installed all of my apps over 150 in multiple profiles, and yet to experience one single app that didn't work or that gave me that error message...
https://developer.android.com/develop/sensors-and-location/sensors/sensors_overview
I can see a use case for allowing motion sensors if you want your GPS app to present your driving speed... I can see a use case for Position sensors which includes orientation but I disabled "Sensors" from all apps and my gallery app (as well as other apps that might need to know orientation) will still flip images horizontal/vertical when I flip my phone, so clearly, that's done without Sensors permissions...
Settings > Security and privacy > Privacy controls > Permission manager - manually takes forever lol, and GrapheneOS could have at least separate them by "allowed" and "not allowed" lists to make it easier as they do in most other permissions :(