Your instincts are wrong, it's pretty much all donations. Ukraine bought some stuff from German suppliers from their own money but the vast majority is refurbished stuff as well as Germany covering Ukrainian orders from German suppliers. 25 million Euro for 5100 anti-tank weapons from Dynamit Nobel, sounds about right for the PzF3.

Companies are certainly profiting from it, sure, but it's overwhelmingly paid out of the German budget. And the companies then again pay taxes in Germany, hard to assess actual cost for the tax payer, also e.g. how much could those old Leos actually be sold for in the state they were in before refurbishment. Especially the US accounting is rather suspicious, there, as they would have scrapped the old stuff which costs money and shipping it over to Ukraine might actually be cheaper.