Hi! As I told another user recently, I am also a Linux user and I registered on this forum with the intention of motivating developers to release a new version for Linux.
I’m afraid the distribution diversity is not the key or limiting issue. In fact, although diversity seems to become the enemy of standardization, it is false that numerous versions would have been a problem in the past. Before Flatpak or Snap, many companies chose to support Ubuntu. At least that way, the packagers of other distros could adapt this package (.deb) and the global problem was solved.
Today, as you mention, there are two “universal packages”. I like neither of these two because both are dependent on two companies: Canonical and Red Hat, and, furthermore, each one has advantages and disadvantages. Instead of collaborating, these companies seek to apportion users to the detriment of all. If I had to propose a single format it would be Appimage, which is very similar to the philosophy of Apple applications. In case you don’t know it, an appimage is a self-contained program with all its dependencies. It’s not great from a security point of view, but it wouldn’t be a problem for an offline application either.
The developer @AmberV did a retrospect in which she analyzes the difficulties and possibilities of re-launching a version for Linux again:
I support your proposal. Hopefully the Scrivener developers would see that there is interest from Linux users and that a community would even form due to the intrinsic quality of their program. I even proposed to correct the Spanish translation for free, as I have done with other programs as a way of thanking them.
Regards.