A validation only allows one to fly an aircraft of registry in the country in question as long as they have their airman certificate, and medical in their possession from their "home country".
A validation does not allow one to earn Euro one in any state/country unless said individual has in their possession a valid work visa/permit to which a job is sought after.
I had to obtain a Brazilian Validation to ferry an airplane from Texas to Rio about 20 years ago. The ferry company was based in the US, thus no work visa/permit was required.
I was inconvenienced
with a trip to Rio, on the company's nickel. It was terrible... the beaches... the food... the beer... and....er hem... I'll spare you the details. Anyway... had to take the medical, and visit the DGCA to get the validation. As I recall, no written exams were required.
I did have to provide verification that I was employed by a US company and was not going to be paid cruzeros before the validation was issued.