I'm a decent developer, but with only a couple years' professional experience and no formal training. I'm looking for open source projects to contribute to (ideally pick one or two and get dedicated to them).
I really hope they add more functionality to Jerboa. It's what I am on rn. There are some bugs I am waiting to be fixed and they should add custom feeds like the reddit app has, so I can have a familiar experience. Also better content previews. Like if there was a way to preview the webpage linked before clicking on it. In-app video player that can support YT and other platforms might be nice.
I mean, it's not Jerboa, but I did (or tried to do) all of that with Tesseract. If you "install" it as a web app (e.g. "add to home screen" from the browser), it's pretty much indistinguishable from an app app. The only "app" thing it doesn't do is system notifications. I'm not sure that's something I want to deal with, though. I have the code mostly in place to support it, but I don't know if I want to deal with trying to keep it running in the background to receive them.
For the features you mentioned:
Custom Feeds: I had that for a while, and it worked, but the Lemmy devs removed the ranking metrics from the API which broke sorting except for date and score before I could get the feature fine tuned. May or may not try to work around that and bring that feature back. For now, the community groups (formerly custom feeds) are just used for organizing communities (which is still useful).
Content Previews: Pretty much any outside link is previewable; it'll pull the metadata, give you the option to try to load it in an iframe in the app (not all sites allow that), and if the link is to a supported media (YouTube, Loops, PeerTube, Spotify, etc), it will render that in the preview modal. e.g if someone comments a bare YouTube link, clicking it will let you watch the video as an embed right there.
Video player: Every embeddable media format I can support I try to. Currently:
YouTube/Piped/Invidious
PeerTube
Loops
Spotify
Bandcamp
Odysee
Soundcloud
DailyMotion
song.link
Vimeo
Imgur GIFs and videos
Direct videos (mp4, ogv, webm) and audio (mp3, ogg, aac)
Cool, I will try it. They have fixed some Jerboa bugs since I posted this comment. But I have now switched to Boost for Lemmy, although they have ads. The only feature I am hoping they fix on Boost is that spoiler text is broken on it.