Feed/topic support would be fantastic. Community discovery is something that’s been lacking in Lemmy for a while, and I love PieFed’s topic implementation. I’d love to implement the topic list in the app I develop.
Worth noting is that Lemmy 1.0 includes multi-communities, which are analogous to PieFed feeds. I’m not sure whether you intend to maintain close parity with the Lemmy API going forward, or whether that was just to help apps onboard initially. Just thought I’d mention that they’ve got a series of API routes for it, in case parity is a consideration.