Platform engineering is the discipline of designing and building toolchains and workflows that enable self-service capabilities for software engineering organizations in the cloud-native era.

Platform Engineering

So a while ago I picked up this book and it has a whole chapter about quantifying metrics from feature inception to sending it out to prod

Basically, you just start with Jira or whatever work system you're interested in, and find the first time the idea was entered into that system, and the day it goes to production. Then just treat it like a span in an application trace and break down the span into smaller logical units that make sense.

We're building golden paths and plan to measure those as a proxy for how effective/ineffective our platform is

Times that a ticket changes state are obvious important markers. Especially states like assigned, in development, testing, and released.

This might give you some insight, not much focus on ROI

You mentioned the DORA research -  they have a new home for their research program. They have a model that shows the predictive indicators for specific practices as they relate to outcomes for an organization.

<https://dora.dev/research/>