First, please don't mix "digital nomads" with the rest: they're a tiny number (in total, ever, adding up to maybe less that 6 months of degree-holder emigration from Portugal) and, worst, produce all the wealth from their work abroad and pay 1/4 the tax of the locals, so each of them isn't economically worth a single local highschool dropout, much less the economic value of the kind of degree holders leaving the country.

The "rest" are even more interesting: basically Portugal is importing people way less qualified that the average portuguese of working age (worse so versus those leaving) and it's being very overtly done to put pressure on salaries in areas like Tourism (which is basically the chosen "silver bullet" to go around all the problems in the Portuguese Economy: I refer you back to my point about just ridiculously bad portuguese management and political culture is) as well as to supposedly make up for the "population aging" (the very thing that was caused and is being made way worse by both low salaries and the policies to inflate house prices).

Pushing out well trained people capable of working in high-value industries and bringing in people with mainly primary school education or less isn't a strategy for improving the country (or in fact "strategical" in any sense of the word, unless there's some kind of strategy to empoverish the country).

Open door immigration is 100% to help politically well-connected Tourism Industry fatcats find workers for their companies whilst paying shit salaries (it's funny how they go on TV saying that they "can't find people to work and need more immigration" whilst refusing to, you know, pay better to attract the workers they need) and exploitative Agro operations growing produce for export who want to pay de facto per-hour even less that the ridiculously low portuguese minimum wage, to try to plug the very problem of "too many old people not enough workers to pay their pensions" that's being caused by continuous political choices to pump up house price inflation for personal profit of those very same politicians and their mates and to increase sheer human numbers for those politically connected companies which are in an economic position to take a cut of the entire GDP of the country (almost invariably holding monopoly or cartel positions due to political decisions) and who couldn't care less if GDP falls per-capita as long as the total number goes up.

The problem is not immigration per-se, it's how it's being done and why (especially if we follow the chain back to the "why of the why of the why" as it ultimatelly boils down to making certain politicians and their mates very rich by sacrificing the future of the country and everybody born in it).

Shit, the only good big thing in present day Portugal which is not being destroyed (even the investment in people in the form of Education, maybe the only intelligent growth strategy in this country, ever, is being corroded and destroyed) is the right to an EU Passport of everybody born here.