I think Wasmachinemann-NL said in the past that he is really attached to pitch adjustment. There might be other things since Rockbox is really a comprehensive software, with advanced equalizer, or a nice straightforward UI that is not gimped with usual gimmicks of modern mobile apps. I am not saying that it is better or not as good as more modern apps, just acknowledging that it is different in several ways, which may explain why many people like it, can't find a proper replacement, and would like it to be maintained. Now, if someone interested has some development skills, I'll leave this here.

Sorry about the off-topic here by the way, just wanted to tell my motivation to test Leste on the Pro¹.