This is it really. We have no idea how much American / outside involvement going on.

It may not even have been a Ukrainian-made missile. Maybe it was a Harpoon, but they're just saying Ukrainian because NATO doesn't want the public credit.

Russia had 100's of advisors in North Vietnam during the Cold War I don't see why the US shouldn't have support units all around E. Ukraine.

Not 100, more than 100,000 Soviet personnel were sent to Vietnam during the war, sometime participated in fighting themselves - [0]

China also actively involved in the war. At the peak of their involvement, 170,000 Chinese troops were present in North Vietnam - [1]

[0] - https://www.rbth.com/history/332396-how-soviets-fought-again...

[1] - https://en.wikipedia.org/wiki/China_in_the_Vietnam_War

We pretty much know that NATO is helping them immensely with battlefield overwatch there are awacs and other air assets 24/7 in the air around the borders of Ukraine. Harpoon is not yet delivered and the operators are still in training as are the ones for the switchblade system so it was most definitely a Neptun.

"Harpoon is not yet delivered" we don't know that.