Changehub has 2 main features.
Changehub parses changelogs following the keepachangelog format. To provide an overview of a project's releases we simply use the Github releases API.
To aggregate a changelog of unreleased features we parse a project's pull requests.
We are actively working on supporting more than one workflow. However it is a hard task to cover all of them since every one works differently.
We understand your concern. Changehub however requires these permissions to access your tags and commit history, and doesn't allow more specific permission requests. We've asked them about that and they are looking into creating these. Should you have any further questions or doubt you can always contact us directly.
There certainly are, we decided to first support Github as it's the most used platform. If there is enough demand we will integrate with services such as Bitbucket and Gitlab.
We don't, but if there is a demand for it we will look into it.
Let us know! directly.!