What server/self-hosted software would you like a desktop/mobile app version of?
Think of some stuff you may already self-host but it'd make it easier (and maybe keep your config simpler) to suggest to others if it had a desktop/mobile app version
For text to speech I'd recommend Kaldi. It's just the android engine and has nothing else to configure/look at, but the quality of the output is really natural. FOSS, fully offline running locally.
I believe so, it seems to have the highest privacy designation on App Store and im pretty sure it turns all my epubs and pdfs into guided audio visual readings without internet necessary or available.
Well it uses Google services in android. Those can still communicate even if the app itself has no network permission. I guess for me the highest privacy designation would be to be FOSS, so people can verify it's not doing anything funny on the back end.