Forgive me if this question has been asked answered already.
I am eager to hear how your companies are structuring the SRE and Platform Engineering functions. Are they in one org? Do these functions ultimately report to the same leader? How are the responsibilities divided among SREs and Platform engineers? Are you SREs embedded with the dev teams?
From my research I am seeing a ton of different models and am eager to hear what is working for teams of 150ish developers.
as another pointed out, i feel you need a combination of expertise spanning "ops/infra" (often called devops engineers, though i don't believe in "devops" as a title), SWE (focused on solid development like building portals, writing custom operators, etc) and SRE (thinking about reliablity of the platform, SLI/SLO, observability and common SRE tasks). this is thinking about IDP at scale. to get started you can obviously have a lot less, but this "ven diagram" is the ideal combination in my mind for a platform to be sustainable as it grows with the right focus on features balanced with stability.
i also like this as more of a "what is idp" and how it might help understand a fit with titles in your organization: