@Madman198237 who do you think have the upper hand in the sky atm? and will adding a couple wings of F16 will change that in any way?
The sky is neutral. Ukrainian SAM systems are doing a pretty effective job of restricting where Russian jets and choppers can operate, because Russia's proven quite incompetent at SEAD/DEAD missions. Ukraine (aided by Western HARMs and guided artillery) has done very well with SEAD/DEAD, but has no counter to long-range AAMs fired from Russian territory, and it turns out that long-rang air-to-air missiles are one part of the Russian military that actually works.
A supply of Western fighters would be a limited solution to that problem, because no Western country has a directly equivalent AAM - the Phoenix is long retired, and neither Meteor or AMRAAM have the same range. Ultra-long range AAMs are
in development, but not ready for service yet. The primary advantages of Western fighters would be the ability to operate any ordnance that NATO is willing to supply (pretty handy, because both HARM and JADM would be much more flexible on a platform they're native to than when kludged onto a Mig-29 or Su-27, and other weapons would become an option), and (probably more important) they would be available in huge numbers. The Polish Migs being given now are probably the very last ones NATO can get, which means that any Ukrainian aircaft that goes down is gone forever. This also increases pilot losses because there's a powerful incentive to try landing a damaged fighter in the hope of preserving a literally priceless war machine, or at least bringing home spare parts that can keep other birds flying. Were F-16s to be provided, a Ukrainian pilot that punched out would have a good chance of expecting a shiny new one from Uncle Sam to arrive by the time he's ready to get back in the fight.
None of this mitigates the extreme practical difficulty of actually getting the things there. Not only is operation completely different (which we know, because so many NATO allies have had to undergo the conversion from East Bloc to NATO aircraft), maintaining any combat aircraft is a nightmarish task. Training any single mechanic is probably simpler than training a pilot, but you need many times the number of mechanics as you do pilots. I would be shocked if there isn't a lot of training happening that nobody's admitting to, but it is a real obstacle.