We do want to take an approach like this in gngr(1). We already have fine-grained permission control in the Request Manager (inspired by uMatrix, nee httpSwitch

We do want to take an approach like this in gngr(1). We already have fine-grained permission control in the Request Manager (inspired by uMatrix, nee httpSwitchBoard). But your question is about even more finer control. Some thoughts: * I believe some of these APIs shouldn't be implemented at all, or should have very limited precision. Eg, Battery Status need not be implemented at all, or if implemented, should return just two values: [high, low]. * In our Request Manager, we could add an extra column for advanced APIs. This would include, for example, Canvas, WebRTC, etc. * @captainmuon's idea of having two different profiles (document/app) is interesting. Though the choice of profile should be on client side. The default should be conservative (document) and the user should get to choose if a site should be promoted to app or not. [1] : https://github.com/uprootlabs/gngr https://github.com/uprootlabs/gngr