Lots of companies claiming they can help tech workers (digital nomads) from the UK move to Portugal and pay 0% tax on income. Surely this can’t be true?

I have attached some screen caps to evidence these claims.

It just all seems a little too good to be true, and with the window of opportunity closing I’m keen to learn more.

Anyone have experience with this?

Here is one such example:

"This is possible, in part, due to Portugal’s 71 double taxation treaties. According to the regime, as long as the source country of your income has the power to tax your income (regardless of whether or not they actually apply the tax), Portugal will not tax your foreign-sourced income.

The list of income sources that will not be taxed under this set-up includes foreign-source self-employment, royalties, eligible occupations,  dividends, capital gains, and investment or rental income."

Many thanks.