Because of legal concerns and because they can be seen as a proprietary asset, etc. it seems vendors have been hesitant to use external tests, or to release their own. So I think a test suite associated with the standard itself avoids those issues the most successfully.
The tests would by definition be runnable so they could also provide useful examples of Fortran features.
Vetting donated tests might take a considerable amount of resources, so I would picture something like a bugzilla approach where the tests could be donated and visible but having to be approved to become part of the official compliance suite.
Whether the standard itself pointed to or included the examples is worth thinking about.
In the past there were several large test suites for F77.
Where the manpower comes from (assuming ChatGPT running on qubits does not make the question mute) for the vetting, or how someone can be selected to approve the submittals? I am not sure.
Having different compiler developers disagreeing on the tests might be a positive or a negative.
It would be interesting to hear what compiler developers want. Is that a useful resource that helps them develop a better product more effiiciently,
or do they not want a large suite available that makes it easier for others to develop compilers (assuming they have a test suite available).
On the wish-list side of things if the more basic tests were fpm packages I think that would make them easily available to a large base of users as examples (so far, you can build fpm from a single file, making it a minimal required infrastructure for all involved).
A testing framework library would be useful. The use of conditionals in the tests is problematic but perhaps a necessary evil.
Any testing framework or other infrastructure requirements would need to be minimal; ideally only needing a Fortran compiler.
Just some initial thoughts. I can imagine additional projects expanding support for the standards committee site and making more manpower available that can contribute to Fortran projects like this even if they are not interested in becoming standards-committee members. So it is not a given that man-power would all come from the current committee.