Did you ever use the official Reddit app? I personally do not like it very much. The third-party Reddit apps were just a whole lot better, at least in my opinion and others. Apps like Boost and Sync were both very popular Reddit apps, but have both now moved on to Lemmy.
Boost is probably just going to be an Android app, since Boost for Reddit was also Android only. I wasn’t sure if the app you were talking about, Memmy, was an IOS app.