Each year, sometime between June and October, CMS releases a detailed database of all physician paid claims for the calendar year, 18 months prior. Accordingly, in July 2022, CMS has released this granular data for CY2020.
Find the database here. It's a cloud database (click VIEW DATA) which can be sorted by doctor name, NPI, specialty, state, CPT code, or more, and any combination of the above. For example, you could get all the labs that billed Medicare Part B for 81162 BRCA testing in 2020, or all the providers who did cataract surgery.
For example, if you look up CPT codes 81410, 81411 for aortic genetics, 40% of the US services were paid to one lab, in Lafayette, CO. One can download all the lab codes by every lab and provider (quite a large file) or all the genetic codes 81000-81600, which are quite manageable in Excel.