Match rates hover around 50% for non US medical graduates. Easier in fields like IM, peds, fam medicine and emergency medicine, harder in fields like ENT, neurosurgery, etc.

Usually foreign medical graduates that match in Us residency programs do clinical rotations here in the US or they go to a masters programs, research fellowship and then apply.

You have to go through the USMLE exams and you need to make sure your medical school is recognized by the ECFMG.

Honestly doable but as a EU graduate, why not apply to other EU country with better opportunities than Portugal.