I have nothing recent about how it goes with the US Cargo operators.
Atlas, Polar, Evergreen, Kalitta etc.
xxx
I left the US airline industry after 1991.
Ex PanAm pilot, I had a few of my ex-colleagues flying for them.
They mentioned using L/M from Europe on their Middle East and Asia flights.
Maybe they still do.
xxx
Suggest maybe you apply with them.
Obvious, you cannot operate US domestic sectors without a US visa.
But you could do their international flights, nothing prevents it, legally.
If you have 747 and/or DC10 experience, even better.
xxx
They often have a fly-along Engineer, and a L/M...
You could be based in UK, or Europe...
Best of luck. Times are hard nowadays.
Happy contrails