Sorry, but your history is incorrect.
Both Muscowy and Ukraine/Ruthenia derive from medieval Kyivan Rus.
Both disappeared into communism (as an aside, the Soviet Republic of Ukraine had a separate seat in the UN from the USSR so was de jure “independent” - if not de facto).
After 1991 the Republic of Ukraine became de-facto and de-jure independent in May 1991. The Russian Federation became de-facto and de-jure independent in October 1991.
So, the current Republic of Ukraine is actually a few months OLDER than the Russian Federation.
One can’t say “they are the same” culturally or linguistically - they are “similar” but not the same - in the same way that the USA and Canada have the same “origins” and are similar but not the same.
Ukraine and the RF started off as very corrupt in the 90s, but since 2000 they have diverged in “corruption index” with Ukraine getting less corrupt and the RF getting more corrupt.
However, looking at purely “what’s in it for the USA” - Putin’s invasion opens up the door to 19th century gunboat diplomacy and wars of conquest - as we saw in the Azerbaijani confidence with Nagorno. This is hazardous to world peace and thereby to the USA’s financial well being.
The USA should not send foot soldiers into Ukraine, but it should not allow Russia to get away with the conquest by force - to prevent THAT pandora’s box from opening.
Not our circus, not our monkeys.
And thanks to that carrot in The White House We The People are funding the pensions of Zelensky’s cronies.
His ‘’ministers’’.
Geez, I wish Uncle Same would fund my retirement.