intro-skipper project dead?

[B C]

attempted to put a request into the githubs for the android apks and was told they will not support 3rd party plugins. not sure why, this seems liek a basic function that works and can be folded into the main app

That is their usual stance on most things, and I kind of understand it. However, in this case they don't need to do much. The plugin is already supported and working on the SERVER, and it just sends control commands to the clients that are playing content. The client PLAYER just needs to support receiving "skip to" commands from the server.
For example, the Android TV client, which is worked on by many of the same people, built-in player does support intro/credits skipping.

Was looking to switch to Jellyfin, but from what you're saying, intro skip doesn't work on certain clients?