Today I received an email by Brenton Horne about another Flatpack like package manager by the GNU Project called "guix" , which I did not know before.
GNU Guix is able to provide the recent stable version of Octave  in a fashion similar to Flatpack:
guix package -i octave
Personally, I would support this, but I did not get it to run yet (my distro openSUSE 15.0 only partially supports GNU Guix. The required service deamons and directories have to be configured manually, or I did something wrong...
The question is, if we advertise this project as alternative to Flatpack on the website . Any thoughts, objections?