For iOS, I use Mlem. It’s open source and updated regularly (the TestFlight version at least). It’s got a really nice interface. Lots of little customization options. Feels a lot like Apollo. My second choice is Arctic. A lot of great options, has push notifications. But isn’t open source (yet!) and feels like it’s slightly less polished than Mlem.
I’m looking for Android equivalent to these two apps, but I’m not see anything remotely close.
I’ve tried it! Both on iOS and Android. Maybe it’s cause it’s not native. There’s something about how it feels that isn’t the same as a native app.