Debian Jessie Client for Nextcloud Box


I have been using Nextcloud Box for several months. I am very pleased that everything worked out of the box. I haven’t been too adventurous by sticking mainly to the Windows 10 client and dutifully keeping the Box updated/upgraded (now that I understand the undocumented steps for recovery). I have three questions, please:

  1. Is there a client for RPi boards that I can leverage to expand the role of Nextcloud Box solution in my eco-system?
  2. Is Nextcloud Box intended for evaluation only or is there a published statement of direction for future releases? The forum activity for Nextcloud Box pales in comparison to the elder sibling of the family for the Enterprise edition.
  3. I have reviewed some documentation but I still cannot build my first plug-in for the Nextcloud Box. What is the recommended self-paced training syllabus?