As for ammo, there is no doubt that Ukraine has ammo producing capabilities and these are increasing.
Afaik there is nothing clever or containing IP about Gepard ammo and if Ukraine was not getting enough they could decide to produce it - as long as they got all the gepards first!
For sure , as per recent press releases they are concentrating on soviet 152mm,122mm and 120 mm mortar production ,these factories having recently been brought online, but there is nothing to stop them from manufacturing basic NATO caliber rounds , it would be surprising to me if they do not already make 155mm ammo on the qt - the S22 Bohdana 155mm SPG ( famously the one of which the single prototype shelled snake island) was just announced as going into serial production.