I lost this thread, perhaps because of the merge.
Just look at the resources used in Iraq to write down their air defense and this is nothing compared to what Russia can put together. Could a full Nato Air Force take the Russian system down to such an extent that they could obtain Air Supremacy, possibly but it would be a concentrated major effort and there would be losses, possibly substantial. Ukraine's system is based on Russia's, now not nearly as effective but has been effective enough to keep the Russian Air Force away. Planes like the A 10 can only operate in a permissive environment.
So not going to happen.
Ukraine basically needs a long range air to air system to keep the Russians away, they seem to be adverse to losses, so probably would not need that many planes with a long range threat to keep them back from the front line.
And a plane that can operate in a dispersed fashion, start building facilities for say the F 16 and they become a very obvious target that the Russians can take out.