Inspired by this comment from @andrewkelly2555, I love the term “secondary specialisation”. It makes sense when quality includes so many different skills and aspects. We can’t be expected to know everything, but having skills spread out over the whole team seems like a sensible idea.
Do you have a secondary specialisation? And if so, what is it?
API security, i would not call myself specialist but more of interests 
When I started in testing, I just did exploratory testing. After a couple of years I started to do accessibility testing and got to the point where I considered both topics to be primary specialisations, although there wasn’t much demand for accessibility back then in the early 2000s.
Fast forward to 2018 and the market for skilled exploratory testing had collapsed and the accessibility market had grown substantially. Since then, I have almost entirely done accessibility testing.
Even within accessibility, I had a secondary specialisation, which was accessible document remediation. I was among the first to do it in the UK in 2005 and again the demand was tiny. But the market exploded in 2020 so I was ready to exploit it just as the accessibility testing market became more competitive.
If you have spent years developing a specialisation, it’s easy to imagine you will be able to do that as long as you want. But things change fast in IT. Whatever you do, salaries and day rates will eventually fall as more people pile in or demand falls as technologies and development practices change.
What was a secondary specialisation could become your new primary one if you choose it carefully (I was just lucky). If not, you could be wiped out, like typesetters and inkbrush artists were when desktop publishing emerged in the 1980s. Those were extremely well paid professions but they no longer exist. Cannonball makers are having a bad time of it too.
Wouldn’t exactly call it a specialization, but I do have quite diverse work experience, in addition to 7+ years in testing:
)My secondary specialisation is the ability to adapt my perspective. Bottom line I’m a generalist, but my background has seen my career go through being a user of software, supporter of software, trainer of software, developer of software, leader of developers, tester of software and leader of testers. I call that a specialism because I rarely see others with that background.
I am a Level Two cricket coach. The knowledge I gained from the coaching course helps me when I am mentoring, leading, supporting, and facilitating.
Coding, and build toolchains. An ability to look at product code changes to verify they actually do address the defect report. I often don’t code much at all in the product languages I test, but I can read most languages pretty well.
Hardware, he works well with hardware. For example, last month , I balanced the power supplies for and wired up a grid of 65 processor cards all into 2 huge ethernet switches and then set up the master controller correctly.
I love this 
It’s a shame many employers don’t see the interconnectedness of skills learned.
My secondary specialization is writing. Initially, I tried to find a content writer’s job but wasn’t successful.
I still write in articles/poems/short stanzas format in Hindi/English/Urdu in my free time and working on my writing skill every day.
I’m not sure, does carpentry count?
No, let’s be serious - I started my career in tech as a software tester, but switched roles back and forth pretty soon after that and often in the past 6 years, to now being a Project Manager. But since I still don’t have certificates to show for any of these roles, imposter syndrome is making it hard for me to even say I have a first specialisation…
Not in the testing Industry I’m afraid..
1- Scientific researcher/ assistant
2 - Office manager
3- Project coordinator ( I coordinated projects in the NGO I co-founded)
4- election observer ( Volunteered for several years with the biggest and the first Tunisian specialised NGO)
5-I enjoy digital marketing ( have even attended Community management and SEO optimization workshops): used it to build a community around the NGO I co-founded
isn’t it just “I - T - N (or Pi) - Comb shaped”? 
The Secondary Specialization referring to “Pi” Shape.
The question is “what’s my primary?” I don’t think there is a primary it’s just all together or nothing! 
