Piefed mobile testing (android only ATM)

No. The app was forked from a Lemmy app (Thunder), so there's not much PieFed-specific in it (e.g. there's also no support for Polls). The exception is that it supports post / comment subscribing (I was notified of your comment, even though I'm not the OP of this post).

I created a new instance for testing the app, and I didn't create any Topics (partly laziness, partly because the whole area is being re-evaluated for user-created Topics, aka Feeds).

The app will lag behind the site in features, 'cos adding stuff for direct HTML rendering will always be easier than adding stuff that's got to come through an API.