Maybe, but eitherway active users is the real metric that matters. Stale accounts dont mean anything.

Fediverse does not need to have million of users. Fediverse only need enough users to mature the technology and ecosystem.

You need to open the post to mark it as read. Expanding picture does not count. There are discussion on improving this https://github.com/LemmyNet/lemmy-ui/issues/384

It is already an option, go to profile settings and unmark “Show Read Posts”.