If Russia's jets can't operate over Ukraine they won't do much in Europe except self-defense of their own homeland.
China on the other hand is a very very serious opponent...
(Edited for a less confrontational beginning of the first sentence.)
Invasion doesn't have to mean they plan to roll tanks all the way to Paris.
Have you realized Russian agents blew up a train in Poland this week, after some weeks prior flying planes and drones into NATO airspace and disrupting air travel in Denmark with drones started from shadow fleet tankers. The grounds for further action are being tested as we speak.
Invasion just means Russian soldiers enter Poland, Latvia, Estonia, Finnland. Countries parts of which Putin painted rightfully Russian territories in his speeches. I wouldn't bet a lot on that not happening, especially if the geopolitical situation deteriorates in favor of Putin.
So invasion means a full war with NATO?
These sorts of wars are very rare in the modern era. They gambled entirely because they faced an army they were 10x the size and they got embarrassed. There's near zero strategic logic in trying again vs NATO after they lost most of their fancy gear.
They would still have to contend with an insurgency on occupied territory, but that is something Russia has considerable experience with, including Ukraine in the past (mopping up the remaining nationalist resistance after WW2).
And despite how things have fared in Ukraine thus far, the Baltics are a much softer target. If Ukraine does end up falling to the Russians, it’ll be used as a springboard by the Russians, potentially supported by Ukrainians disillusioned with the West’s betrayal. It would certainly not be the first time that Russia has annexed Ukraine and mobilized its people against Russia’s foes.
Reversal of what Russia sees as a great injustice. The 2021 ultimatum[1] issued on the eve of the war can be summed up as a return to the Europe of 1989 with everything that it entails.