I can only think of a few licensed stallions in Europe that were bred and born in the U.S.:
Tzigane
Lord Luciano
Validation
I believe Tzigane was originally licensed here by ATA, and later presented to the Trakehner Verband in Germany. I do not know if he met performance requirements via testing or via performance, not do I know if he is licensed by registries other than Trakehner. I know the Trakehner performance requirements are somewhat different from those of the other Verbands in Germany, so he would need to meet the requirements of the other Verbands in order to be approved by them.
I also do not know if Lord Luciano did a performance test in Germany. Anissa, do you know?
Validation was originally licensed and performance tested here. Since he was licensed by several organizations with reciprocity in Germany, and he passed performance requirements at a testing recognized and approved by the FN and German Verbands, he did not need to be re-presented in Germany to the mother Verbands of those U.S. based registries, nor did he need to meet additional performance requirements to be considered approved by those Verbands. (Barbara, please correct me if I am wrong).
But to answer the OP’s question: To my knowledge, there are only three registries operating in North America with full reciprocity with their “mother” Verbands in Germany - AHS, OHBS/GOV, and RPSI. Colts registered with those registries could be sent to Germany for stallion inspection. If licensed, and if they meet the licensing organization’s performance requirements, they would be considered fully approved by that organization in Germany and by its North America counterpart or daughter organization.