There is a self host sync plugin for obsidian (I’m assuming you just want to self host not any other specific reasons)

https://github.com/vrtmrz/obsidian-livesync

I currently use it with a self hosted docker instance of couchdb

https://github.com/vrtmrz/obsidian-livesync/blob/main/docs/setup_own_server.md

Edit alternativly their is Joplin (but not sure about how you used obsidian/zotero)

https://joplinapp.org/

https://github.com/laurent22/joplin/blob/dev/packages/server/README.md

https://github.com/tborychowski/self-hosted-cookbook/blob/master/apps/notes/joplin.md

Smart AudioBook Player (Android) https://play.google.com/store/apps/details?id=ak.alizandro.smartaudiobookplayer&hl=en_US&gl=US

I primarley use it in combination with google wavenet/ Elevenlabs to generate audio books from light novels (for personal use)

Biggest reason I like it is wavenet/eleven labs tends to generate 1-2 min mp3 files. Smart audio book allows clustering of these mp3 files (merging total listening time).