As a fun project, I started developing an Android app for myself a few weeks ago, because I already missed Boost for Reddit, even though it's still usable. So I took Boost as an inspiration and started working. It's come quite far and I have decided to publish it on Google Play, in case others feel the same way. It's still lacking some features, most notably the ability to see when someone sent you a message or replied to your comments, as well as the ability to create posts, but for casual lurking it's already quite nice I think. It will hit Play Store in a fews days.
Will it be open-source?
I'm not sure yet. Right now it's not, but if the majority of people wants it to be then I'd oblige. I have zero experience with managing open source projects though, so I'm not sure if it's a good idea
You don't have to manage it.
Just publish the code and keep developing for yourself. That way either someone can fork it if they want to or if you drop of the world...
You just have to manage it, if you want to incorporate PullRequests or let someone else join in the development...