While using the app myself I ran into a similar “issue” where subscribing to a new community would take quite a few steps. I’ve been playing around with the idea to nest the community menu inside the post menu, which would reduce the amount of steps. I’ve been trying out the following setup:
In parallel I’m working on a bigger update that includes notifications and widgets, so it might take a bit longer to release this update. But hopefully this makes your requested flow to block communities a bit easier (: