To get back to the original topic of this thread, "Qt "stuck" at v5.6 in SFOS" and in this very context "Jolla's relation to the *GPLv3 license family", they have achieved a little step:

As denoted in the IRC community meeting log of 2021-02-25, Jolla ceased to avoid GPLv3 software in general.
Instead they started distributing GPLv3 software as optional RPMs for SailfishOS, i.e. what formerly was (until SailfishOS 2.2.1) in the mer-tools repository. Now (since SailfishOS 4) only the RPMs for the basic SailfishOS (i.e., which may be installed by default) are still kept free of GPLv3 software.
For example, this change in strategy allowed Jolla to update the historic, last GPLv2 version of bash (v3.2.57) to a recent bash v5, but only as an optional RPM. Side note: At the same time a recent busybox version of ash is installed by default (which carries a "permissive" / "weak-copyleft" license), along with a symlink which calls ash in its (limited) bash compatibility mode.

Well, to put this into context, that strategy change addresses half of point 3 of the identified items Jolla could be asked for.
And while this is nice and viable for small, interchangeable tools (as a UNIX shell or UNIX command line utilities), applying this scheme seems to be technically hard to infeasible to big, local infrastructure components, as ... Qt with all of its components.

IMO the major takeaways from this license strategy change are:

• Jolla has shown for the the first time (in 7 years), that they are not only "thinking about addressing license issues" (as they stated so many times), but are also able to further develop their license strategy (just a little, this time) and to execute that in practice.
  Even though this is a small step taken now, I think "execution over blah" cannot be overevaluated.
• For the first time Jolla is willing and able to clearly communicate an aspect of their license strategy (i.e., aforementioned change) publicly, though only when asked and with a tiny audience (IRC community meeting).
• Jolla sounded much more confident in recent IRC community meetings to update Qt beyond 5.6 "soon" (well, we know that Jolla slang means "some time").
  Sadly they provided no indication how (WRT licenses); I guess we will know from the header files, when it happens, but not before that.