How technical are you with any given solution you are working with the team on?

It can vary from not-terribly-technical to quite technical. This depends on how complex your product is and how much the nuances of that complexity matter to the user's success with it. As an example, GitHub Actions has sophisticated features like matrix builds for parallelization, required and reusable workflows, and others where the design, down to the structure of the YAML, matters a lot to the end user. But even in Actions, these are corner cases.

What's important is that developer product managers not be afraid to dive as deep as necessary into technical details. Now, 95% of the time, do they need to be reviewing engineering design documents with a fine-toothed comb? Largely not, assuming that their partnership with engineering has been going well, and also that engineering has enough empathy about the end-user to make the right call even at a low level of detail.