how long does it normally take until a plugin pull request is merged?
I ported my plugin to work with volumio 3 and the pull request has been open for 9 days.
Who is responsible for merging?
You should note that volumio 3 and its acceptance depends also on available plugins.
I don’t think there is a number to put on that AxLED. It’s a new plugin system, and there are a lot of resources going into bug-squashing at this time obviously. Sorry, but it will be reviewed asap, as fits in with priorities.