Use a device with a web browser as speakers for another jellyfin player. Kinda sucks at syncing also relies on said player being compliant with sending playback state to the server frequently enough (spoiler: many aren't). syncing kinda sucks rn, goal is to get within 10ms error margins, but this is hard esp on low powered device web browsers (likely want to write a native version sometime).
javaarchive/syncfin
use a device with a web browser as speakers for another jellyfin player
TypeScriptGPL-3.0