Brucehankins I think quality is a relative term also, in some areas at least. Things like ux (appearance, layout, design) may be of high quality to one set of users while also being of poor quality to another set.
That is certainly true, but I would submit that generally accepted modern design standards exist for GUI apps, and that goes beyond personal preference.
All major Windows, MacOS, Android and iOS apps, although often quite different in appearance, layout and design, are remarkably similar in terms of meeting modern design standards. Major Linux apps (e.g. LibreOffice) do so, as well.
But many Linux apps fall far short of the mark, designed, it would seem for 2001 rather than 2021. The apps are functional, but not up to the design standards that Windows, MacOS, Android and iOS users expect.
I use LinSSID, for example, a completely functional app that seems stuck in the Windows XP days in terms of design, when compared to competing Windows/Android/iOS apps with the same functionality.

The outdated UI** doesn't bother me, but I think that a Windows/Android/iOS user, comparing the apps that they use on those platforms, would look askance.
My comments about quality were made in the context of Torvald's remarks a decade ago to the effect that Linux would not gain a significant market share unless and until the Linux community developed enough self-discipline to focus on quality rather than quantity. Torvalds was speaking in context -- to gain market share, Linux has to directly compete with Windows and MacOS, and I think that Torvalds, when thinking about quality in that context, was speaking about then-current generally accepted GUI design standards. At least that is how I interpret his comments.
A significant number of Linux apps were behind the design curve then, and it seems to me that, in light of developments in both Windows and MacOS GUI design over the last decade, not to mention the advent of Android and iOS apps, that a significant number of Linux apps are well behind the design curve now. Users expect apps to meet modern design standards, and are right to do so.
Brucehankins Strictly looking at functionality could be a better option. Does it do the thing it says it does without breaking? Do all features or functions work properly as stated?
I think that functionality (in the sense that you are using the term) defines the bare minimum threshold of what is acceptable. Any app that doesn't meet that minimum threshold should not be in any repository, period.
Brucehankins Functionality of an app is tested and verified by maintainers and team members before an update is pushed or an app is included (my assumption) in the Solus repos.
That's my understanding, too, and one of the reasons that Solus remains rock-solid.
**Edit/Update:
By way of comparison to LinSSID, this is the app used at the railroad, available for Windows, Android and iOS:
