This is already in the app, just go to Settings>Advanced>Media Viewer and enable “tap to dismiss”

I’m on Jerboa now, but the lemmy mobile website is pretty good. I prefer the mobile website to some of the other apps I’ve tried

I think it still works if you are a mod or modded a sub at some point. My main account where I once created a sub before promptly deleting it a few years ago still works, while my alt account no longer works.