You do realize these claims were disproven literally the same day these bullshit surfaced right?

The only things that did make it to "market" were spent javelins, with no launcher screen. They are one time use weapons, people were selling spent tubes. Which by the way, you can buy from Army Surplus auctions legally in the united states already.

Ukraine has S-300 systems already.

This is an additional system, the systems are fairly massive(Consisting of Radar, Control modules, several/dozens of launchers each). S-300 systems are not small, but Ukraine does have up to 100 batteries and 300 launchers with 21 confirmed launchers destroyed.

What greece would be donating is 32 launchers, roughly 4 systems.

Now keep in mind we only know Ukraine lost 21 launchers, likely they have lost more, and generally it was predicted only about 40% of them even worked prior to 2022. Ukraine has ramped up repair and reservice of the systems but that could take over a year or longer to bring online older systems or salvage usable systems.

Either way, 32 additional launchers and 4 additional systems is good news if ukraine gets them. It's just more to cover more area so less gets through.