Thanks for the suggestion!
This is an interesting idea, but it is quite platform-dependent. On Android, this kind of data may be possible through Android’s usage statistics APIs, but it requires the user to grant a special “Usage access” permission, which is a very broad and privacy-sensitive permission.
On iOS/macOS, Apple’s Screen Time APIs are much more restricted and are not a simple general-purpose feed that Diarium can read and store like calendar or fitness data.
So this would not be as straightforward or cross-platform as some of the existing integrations, but I’ll keep the request open and see how much interest there is. If implemented, it would need to be strictly optional and clearly explained to the user.