I wish HN had a way to save a story without upvoting it or showing it publicly on your profile (the "favorite" feature implemented right now), like Reddit's "Save". Many times I'm interested in something to check out later but it's not something worth upvoting (like this story, based on other comments) and I want my interests to stay private.
This issue is better solved externally - using a bookmark manager. It would allow you to have all your "read later" links in one place rather than being scattered over different websites. Personally I use Safari's reading list feature for that.
Quite a few people were unhappy when twitter renamed "favorite" to "like" because they had used it as a bookmark and did not want to imply advocacy. Seems like both intents could be supported fairly easily.
No, Watch emails you a bunch. Stars just show up in a list so you can find it later. That being said, public bookmarks always seemed weird to me. Why not just actually bookmark it with your browser? Not that it matters.
App provide better UI and UX for mobile devices. It's faster, easier to navigate (bottom navigation) and some features work in it which don't on the mobile site (I can't remember which views force desktop view).
I know, that's what I'm saying. We were talking about stars and then you said I should look into Watches instead, but what I was saying is that I don't like watches because you get emails. Customizing which emails doesn't help with that. Apologies if I was confused about something.
You may want to revise your judgement, GitHub added support to watch on "custom events", such as: new issues, new PRs, new releases, etc. You might want to try again.