These points don't address all of yours, sorry, but may be of some use?
- "Psicologia Social e das Organizações" seems to be the closest thing in Portugal, and is a Masters level qualification following on from Psychology degrees, offered by several higher education institutions. So, in that sense, it is "a thing" here.
- Degrees must be officially recognised in Portugal, in almost every circumstance (short of informal work, or employment by someone you know well, where effectively they're taking your qualification for granted). Information about whether recognition is possible, and how to do it, is here: https://www.dges.gov.pt/en/pagina/degree-and-diploma-recognition
Note that there are costs and complications to doing this, so I would check this out before embarking on any further courses of study outside of Portugal - each qualification needs to be separately recognised!
- Professional recognition/membership may be required to practice officially in Portugal - I do not know enough about this field to be sure, however it's common for professional membership to be required in order for a professional to be able to practice (in some/many/all circumstances). I am guessing the relevant body is likely to be https://www.ordemdospsicologos.pt/pt (there is limited English translation via a slightly hidden button top right)
Unlike the US and the UK (amongst other countries), career paths in Portugal (and much of Europe) are often highly regulated, with pathways through education and internships leading to professional memberships, prior to professionals practising independently/being hired. There are pros and cons to this approach, however it is a cause of frustration for people moving from countries with a more flexible approach.
As a concrete example from another field, a fully qualified, experienced architect with a history of practice in another country would need to get their qualifications recognised, and then join the Ordem dos Arquitectos (which could require additional courses/work experience, potentially - and a large fee), before being able to officially work as an architect in Portugal. Without this, of course the architect could prepare plans for people, advise them, etc... but they could not submit planning applications, or appear as a licensed professional in connection with any project/works - and this in turn significantly reduces their earning potential and possibility of being hired. We know people in precisely this situation, working two jobs of the supermarket checkout kind, to be able to afford conversion courses and professional memberships, after years being practising architects in their countries of origin.
The point here is not to be negative - but please do thorough research starting from "what is needed to practice professionally in Portugal?" or "who might hire me, and what do they need me to have?". Personally, unless you can identify specific employers, I'd start by seeing if the Ordem are at all helpful!