Unfortunately Armbian has changed their support mode for unmaintained Board and no longer makes downloadable images if the board is not supported. (Not complaining, I completely understand). I am looking for a nice, downloadable image so I don’t have to build my own.
None are really “discontinued”, but OS images are no longer being generated automatically unless there is a board maintainer. There is a list of board status somewhere on their website. Let me see if I can find it.