I think the intersection of Qualitative opinions and Quantitative metrics (for the bean counters) is best captured with formal surveys.

Surveys let your audience provide qualitative feedback in a structured way so you can present it as more than anecdotal evidence (which cherry-picked tweets feel like).

The key is to create a survey that you can run regularly, establishing a benchmark, and then showing progress against that benchmark on "soft measures" like awareness, sentiment, Net Promoter Score, etc.

If DevRel takes ownership of this surveying process and presenting the results, they can more easily own the trends and defend the actions that support them.