Your result
Portugal — Digital Nomad
Possible
This is workable, but the mix is the thing that decides it, and it is worth structuring before you apply rather than explaining afterwards.
The remote-work route requires the work to be performed for individuals or companies domiciled or headquartered outside Portugal. It does not say you may never invoice anyone in Portugal, but the visa is granted on the basis of the foreign relationship, and that is what you have to evidence: contracts, invoices and payments from outside Portugal.
Two practical approaches. If most of your income is from abroad, apply on that basis, with the foreign contracts and three months or more of payment history, and keep the Portuguese work as a secondary matter. If your income is substantially Portuguese, the honest route is the independent-professional one instead — a residence visa for self-employed work with a Portuguese contract or promise of a services contract, registration as self-employed here, and social security enrolment.
There is a third case worth naming: if the Portuguese side is a business you would be building here rather than clients you serve, the entrepreneur route exists, including a version for innovative projects hosted by a certified incubator, which has no capital threshold.
Whichever you use, the permit that follows is the same shape — two years, renewable for three — and the time counts towards naturalisation.