For the most part the Central Powers and Axis were restricted to what they could acquire on continental Europe.

That is because of the effectiveness of blockades. The Royal Navy and Entente in WW1 was deftly able to cutoff almost all outright imports to Germany or Austria, While some neutral hand waving shipping was able to come through neutrals like the Netherlands outright war machinery was much more difficult to get through. Same story generally with WW2 except the previously huge German Merchant Marine was nowhere near the same size, while Germany had gobbled up several other notable factories and companies such as the Skoda works to augment their production, while Norway provided some additional production.

There are a few interesting cases though where a company produced such a good weapon and in so many numbers that it was sued by both sides. I would point out the Bofors 40mm cannon as one example sued in large numbers by both Allies and Axis, and still in use today, it is just a solid reliable adaptable design. Another was the Oerlikon 20mm cannon which was virtually the most common light anti aircraft cannon of the war for the Allies and derivatives were used by the Axis in that role as well as usage as a main armament in early war fighters and Night Fighters. Because of the location of their factory in Switzerland Allied models were mostly built under license as well as some domestic German production too. As with the Bofors the Orelikon remains in use today as a point defense weapon aboard naval vessels.