Can anyone explain this:

OS tend to have a 'last version' of a browser that will work without additional dependencies.

Despite the fact everyone will tell you to upgrade the OS, say you're in an old distro & the last version of Chrome to work is 90.

In my distro every Chromium-based (90 equivalent) browser will work, but not the Chromium appimage (looking for GLIB 2.27, ..8, ..9 for a start).

How are distro-independent app packages supposed to come together still requiring basic dependencies the commercial products do not need?

is this still the same issue? https://www.linuxquestions.org/quest...um-4175733988/

The problem is that the app (appimage) assumes at least a basic environment to be able to run. It needs a working OS with a minimal set of features (like display). In your case the OS is too old and does not provide the necessary platform to run your appimage.
Distro-independent packages are actually not fully independent solutions, because not all requirements can be eliminated. It is just impossible.
In the end, you will see that the current appimage releases will probably only work on the currently live and maintained distributions, not all of them. Especially not on the dead ones.

No

There I was looking for Debian dependencies. Here is about appimages. same browser

well said

Essentially unitary app packages are not as advertised & offer other advantages, like security and single-file simplicity where they work, the second a big factor in determining usefulness of the format.

I make app packages all the time, but they are not the same ones everyone else is using hence not in all the popular distros.

Now which common varities are the easiest to make... hmmmm