When talking about testing shifting left we might confuse things, as it can be both about early testing about technical testing and about test engineering.
Getting testing in early means being involved in the early discussions about the product – be ind the bid teams or be involved in the early wire-framing of the solution. Perhaps being involved in estimation and project portfolio planning. There are many ways to do this, and it always pays off to be a little ahead on things.
Being a technical testers, to me, means getting under the hood of the application. Getting into the log files and transport requests. You might be using POSTMAN or SOAPui or python shell scripts. All these things are tools that supports testing.
The next level (it’s a spectrum) is the test engineers, that similar to software engineers primarily write code to be run in an development environment or maintain a testing framework. Depending on the size of the organisation this can be a full-time role or a temporary role in a team.
One of the three viewpoints does not imply the other, So keep an eye out for the differences. Contexts matter