Portugal has snuck up on other countries several times in history.

They are a small European country most Americans think is in the Middle East or Africa. They have managed to make their language the dominant official language of the largest country in South America.

Now they are making their area a digital economy tax free zone.

https://cointelegraph.com/news/portugal-tax-authority-bitcoin-trading-and-payments-are-tax-free

At some point in the future digital currencies will overtake fiat, and all countries will consider nonfiat digital currencies to be 'global property', and not taxable by a fiat interest. But that may be far in the future, so it is an unusual move by a fiat nation.

What are the advantages?

There are actually almost nothing but advantages for Portugal. A much easier list would be drawbacks.

There will be a slight loss in tax revenue, but that will probably be more than made up for by increased fiat volume as a collateral effect of digital growth. There will probably also be an increase in scam coins and other digital crime based in Portugal, but Portugal could make a clear policy of 'zero taxes, more strict enforcement of existing criminal laws as they apply to the digital economy'.

They could sneak past the so called 'digital economy zones' that some countries are trying to create and re establish themselves as a significant power while the rest of Europe is fiddling over politics.