That is why I said they work great if just funding an insurgency, they are great for surprise attacks against lowflying aircraft, but do not work for much else.
Ukraine needs a unified system, which is armor, trucks, artillery, etc etc to not only keep up a defence, but also to keep their logistics rolling.
The hawk would work fine, however I doubt the west will give them any. Ukraine still has some s-300 systems that survived working as standalone units, though there has not been much recorded on their use recently, so they likely are either running out of missiles or saving what they have to defend vital areas of kyiv.
Actually, the Hawk would be great for both.
Especially as they are highly mobile, a dozen HMMWV or similar vehicles can move an entire Battery of launchers. And even better, as they operate by RADAR.
And more than that, simply by being there the RADAR demands that any aircraft in the area pay a lot of attention to them. Hell, just sending them a few dozen RADAR systems and little else will start to drive the Russian Air Force nuts. Not unlike what Saddam was doing in 1990-1991 and 2003 with the "SCUD hunts". Set up a RADAR someplace, and start radiating with 2 or 3 more a mile or so away each. As soon as an aircraft is detected, it powers off and moves then another fires off just outside of the range of the aircraft.
Rinse and repeat.
The beauty of HAWK is that it is highly mobile. Literally it can be ready to move in under 10 minutes. Just send them a lot of FOCA fiber optic cable, so when they can abandon it and move to the next location.
And that is the biggest problem with the larger and more capable systems like S-300, PATRIOT, etc. It is "mobile", in the sense that a CASH (modern variant of a MASH) is "mobile". It can be moved, that is about it. Roughly an hour at each end to set up and tear down, not counting movement time. And with the size and weight, restricted to main hardpacked roads. Something not really very available in the current area where much of it is soggy.
You must remember, we are now talking about my specialty. They can have dozens of S-300 left, but that will do them little to no good at this time because the things are not well suited to this kind of operation. This is indeed almost an insurgency kind of setup, and not a major battlefield which is where GRUMBLE-PATRIOT was designed to be operated in.
You have to realize, for those systems it was expected that the side using them would likely have either overwhelming airpower, or they would be operating in an environment where aircraft would be so busy operating against other aircraft that they simply defend select positions and not have to worry much about moving or being attacked other than for SEAD missions. Let's just assume that this was really a WWIII situation, and the target was not Ukraine, but Germany.
There, the US could not be sending aircraft to "Germany", because they would not be operating them from there. The aircraft would be operating out of France and other nations, and flying to and from Germany to do their attacks and defenses, then returning. Safe from Russian air attacks themselves at bases removed from the front lines. And even better AWAC aircraft so the air defenses can spend a lot of time powered down, undetectable to enemy forces.
But Ukraine has none of this. No early warning aircraft, no friendly bases to operate out of that are out of reach of Russian forces.
You are talking "unified system", and so am I. But the question is, do you know how such are set up and run? I do.
And in reality, HAWK has largely been retired for decades. But many countries still keep them for reserve forces, or for deployed forces. And the US has many hundreds of them still sitting in boneyards across the country.