I've seen the app Apollo as the center of the reddit protest (it was mentioned and cited more than any other app in relevant posts). I've also seen many Lemmy clients in development taking inspiration from it.
As a lifetime Android user I've never been able to use it, and I've never gotten a proper answer to "why not just use the official app?" What made it different from the official application and other unofficial clients that consequently made it so popular among Redditors?
The user experience. It was fast, easy to use, visually appealing, and the actions were intuitive. It honestly had everything going for it, and performed better in areas where the official app lacked.
Yes. Apollo had a near-flawless interface. Christian kept smoothing up the experience until it was a dream to use! Because he listened to his users and built in the most popular functionality requests. And kept fixing stuff that broke due to changes outside of his control.
Example: at some point a couple years back, links to YouTube videos no longer consistently worked (some could no longer be played from within Apollo). Christian added a feature so Apollo would open the phone’s YouTube app, load the requested video there, and start playing it.
Also his work to make gifs act like YouTube videos comes to mind. In Apollo you could scrub forwards and backwards in a gif, mute or play the sound where available.