The distinction now is whether you have a European Digital Covid certificate, or a certicate which is aligned with DCC - not the country from which you are arriving. So I went from USA to Portugal without needing a test since I hold the NHS app, which is aligned to the DCC. If I went from France, UK or pretty much anywhere then no tests needed. However someone without that DCC or equivalent - for example someone with the US CDC card - would need to get tests whether travelling from France, UK, USA or pretty much anywhere. It's just travel within Portugal and their autoonomous islands that is exempt from this criteria.