There were endless moments in season 3 that would have been solved by reaching out to the progressive Borg collective from the season 2 finale. Not to mention that a few character arcs and character development moments that just seem suspiciously absent in season 3. So, is the entirety of season 2 not cannon or am I missing something?
Well, that's a decision you'll have to make for yourself. I happen to have grown up on DS9, and in my heart there's not much room for Worf's Wacky Adventures on Risa; people a couple years older than me tend to have performed some personal, private retconning of at least one episode of TNG's first season–if not more. And I have just finished the novel "Spock's World," and realized I wish I'd read it years ago and some of the thing's Diane Carey wrote in that exceptional book are better than the contradictory idea's Paramount officially introduced in later media.
What season 2 of Picard means to the producers is far less important than what it means to you–and if it inspires you to go back and watch TNG, you may want to jump straight to Season 2 of that show, as well.