Go to Canada and pay $100, take a test and voila you have a CDN ATPL.
If you have a right to work in Canada you are set.
It cost me $4000 to convert my license from Canada to the USA. Mind you that was 10 years ago and the US Regs were a bit different.
15 years ago if you came from Europe and had a ATPL you would get a FAA commercial with a stamp on it that said "Not for Hire". You would then have to take a flight test and written to get the restriction removed.
I don't know why the regs changed, or for what reason. Maybe to increase revenue for flight schools in the US. Tighter regulations is doing nothing for GA in Europe. Maybe we should be thankful for the income of foreign students.