That’s not even correct on a technicality, because you switch mid-sentence from discussing “war” to discussing “declaration of war.” A declaration of war is plainly different from a war. Declarations of war are frequently made well after a war has begun or well before any fighting takes place. And as you state, many wars are fought without any declaration of war.

I'm unsure the US can unilaterally decide if it's in a war or not. Do the opposite side consider it a war? Do the international community consider it a war? Semantic games internal to a single side do not matter much.

Until an outside observer collapses the wave function, it’s a Schrodinger’s conflict? A Tolstoy Superposition (of War and Peace)?

You are using the word technically wrong. Whether a country is at war or not is not a technical matter, it is dependent on the facts on the ground. A war is an intense armed conflict, usually between states. Just as the US did not declare war after WWII, they have not had problems calling Russia's invasion of Ukraine a war, despite Russian statements it is just a special military operation. We all know it is a war, just like that the US has been involved in multiple wars after WWII.