Hello Dr. Ryil,
One source of national averages is Head Start CLASS scores (Pre-K only). This dataset does include dimension averages, but unfortunately, with the pandemic, the latest data is a bit old and was released in 2020. Here is a link to these results https://eclkc.ohs.acf.hhs.gov/data-ongoing-monitoring/article/national-overview-grantee-class-scores-2020
As for access to your data with your certification test, I am attaching a screenshot for your reference. You can see your results by clicking your Certification tile and clicking Report 1 under your recent test. It will give you a break down that you can use. I hope that helps!
All the best,