If you haven’t watched all of Picard, “All Good Things…” (TNG season 7 episode 25) and “Endgame” (VOY season 7 episode 25), please be advised there are major spoilers.
This may come down to a personal interpretation: did the events of “All Good Things…” ever exist? There is one reason I ask this: the false positive diagnosis of irumodic syndrome. The way I see it, the events of that episode are rendered non-existent.
Jean-Luc assumes prior to his death in season 1 of Picard that his illness was irumodic syndrome. However, it is never specified in that season that he has the illness. In season 3 Jack Crusher is diagnosed with it and assumed inherited. However by the end we learn it was a condition related to his time as Locutus of Borg.
In VOY, the future timeline with Admiral Janeway appears to be connected to the anti-timeline future from “All Good Things…”. The Admiral wearing the same uniform and badge. However the big difference is that the present day Prime Voyager is aided by future technology. We do not see the influence of Admiral Janeway get reversed, only the events of her future.
So did the events of “All Good Things…” actually occur or did the temporal incursion being fixed rendered it non-existent? After all, Q was testing Jean-Luc. Only Jean-Luc had memory of what happened. Sub-question: did Jean-Luc actually have a correctly diagnosed irumodic syndrome in the anti-timeline future?
Regarding the future uniforms, the same uniforms appear in most portrayals of “future starfleet” during the TNG era, such as DS9 The Visitor. I don’t believe they are meant to indicate a connection between alternate futures beyond being the next step for Starfleet uniform designs (although the uniforms shown for a similar time period in Picard turn out to be different anyway).
Regarding your question more broadly, yes. And also no. Both, really.
I’m not sure Q recognizes or cares about the distinction between spinning up an entirely bespoke simulated reality for Picard to do his thing in, versus altering the past such that branching timelines are created and shuttling Picard’s consciousness between them before ultimately closing them off. Or whatever other myriad mechanisms an omnipotent being would have for triggering the events portrayed. Nor is there any real way for us the viewer or Picard the participant to distinguish between those things. What is real, what clearly matters both to Picard and to Q, is that Picard did pass a test, and that Picard remembers those events in a way which will influence his future actions and relationships.
I didn’t bring this up before because it wasn’t relevant, but we see the “All Good Things…” badge in PRO, which a conversation between Admiral Janeway and Hologram Janeway confirms was a design copied from “Endgame”.
EDIT: Which is great because if Cosermart never make a AGT uniform, I can get a PRO uniform and wear it together.