Swiss
Don't know the answer bar with the Swiss who needed special permission to recruit foreigners. The luftampt accepted SCPL and Atpl subject to a swissair course that included air law which opened my eyes as different to the UK law. (Germany and Switzerland mixed VFR and IFR traffic in controlled airspace which the Brits didn't nor did my old opos know).
At the time 23% of Swissair pilots were foreigners, mainly German and Dutch.
Crossair established their base in Basel Mulhause which was in three countries amd enabled to recruit worldwide including Russians which led to one total loss through misreading the artificial horizon (they indicated in a different sense).