The Poles will invade and "occupy" Western Ukraine as part of a "peacekeeping mission".
They want to revive the old Polish-Lithuanian Commonwealth, only this time with Ukraine.
I suggest you google the "Polish-Lithuanian-Ukrainian Brigade". They are a military force that is probably already fighting in Ukraine.
When Ukraine gets their F-16s, they will need air bases from which to take off, bases with very long and pristine runways, and special repair facilities in which they can maintain the planes.
Ukraine has no such air bases, and if they try to build one, the Russians will drop a couple of Kinzahls on it before they can even get one bird off the ground.
Poland will allow the Ukrainian F-16s to operate out of Polish air bases. And then it will be up to the Russians to attack those bases.
And when that happens ...