Well, actually, PieFed.social has enabled it’s API which means that the Android app Interstellar can be used with it. Find out more about the app at https://interstellar.jwr.one/.
Later today https://feddit.online, another PF instance, will enable the API too and I expect others will follow in good time.
The app requires an existing login to use, right? I tried the app since the website’s email/password registration screen just returns “An unexpected error occurred” every time I try it, but didn’t see a new registration option for the app, just the login option.