Can we allow pinning hashtags to the side bar, so that people can click on it and see all the notes with that hash tag? Or even better, allow saving search to the sidebar (in which case the hashtag will be a special use cases since we can search by hashtag). It’s like a virtual category, but allows …

Yes, you can already save searches when you have the premium features, and you can save a search for a tag to achieve this. We have plans to make it even easier to make tag overviews too.