It’s not like manufacturers had much choice in what they produced back then, the Nazis had a command economy. It was basically be expropriated or do as we say. The whole Nazi accusation stuff goes deeper than that, though, in particular, it includes a whole family feud:

During the war Rudolf Dassler was called to the front, while Adi Dassler stayed home. Rudolf came to believe, and the truth has never been properly established, that Adi pulled strings to have him sent to the front and after the Allied powers first shut down the company (because war supplier) and then re-opened it (because Jesse Owens) Rudolf told the Allies about the forced labour aspect. Frenchmen, btw.

The brothers quickly became irreconcilable and split the company. Rudolf then founded Puma taking with him basically all the sales staff, Adi was left with a ton of shoemakers and re-named the company Adidas. Their families and companies are feuding to this day.

That is to say: You don’t impress Adidas by saying “boycott Adidas”. Go with “buy Puma”, instead.