Hi,
Well, to be totally honest, from my point of view at least, it's indeed not 100% clear what the meaning and future of the GlassFish Server project is. This question has been raised before and I don't think we arrived at a very clear answer.
The GlassFish application server is individually distributed and certified by various vendors, either directly like Primeton Appserver or with some changes like Apusic ASS or with some more changes still like Hitachi Cosminexus. A somewhat special case is Payara, which once derived from GlassFish, but has now innovated greatly on top of the original code base and has thus become more of a server of its own (disclaimer, I worked for Payara).
Payara and Hitachi together lead the GlassFish project and are generously donating resources to push it forward in the way we're seeing it happen now, as is the previous owner Oracle. But none of them market or directly publish GlassFish itself. As Steve from Payara has indicated, the community needs to step up if they want to see more happening. As an independent contractor I'm one person who dedicates some time, but I also have the work for my customers to do, so that's unfortunately quite limited.
Hope this makes it a bit more clear.
Kind regards,
Arjan Tijms