My husband had both tests done and it is good that you are doing this research since indeed some therapy choices can be adjusted depending of the mutations present in your cells.

Germline tests you can order for free. Here is the link for that discussion :
https://connect.mayoclinic.org/discussion/promise-registry-and-genetic-testing/
Somatic tests are usually ordered by your doctor - my husband's surgeon sent PC cells to be analyzed upon our request. My husband has 3 types of mutations on his cancer cells and none that are inherited. We did not get much information about his mutations since perhaps those mutations have no effect (as of now) for his treatment plan. He had localized cancer and so far only RP done.

You probably saw this article in your search, but just in case I will attach the link :
https://www.pcf.org/somatic-and-germline-genetic-testing-guide/wp-content/uploads/2025/10/PatientGuide-Testing-web.pdf
I wish you super successful treatment and please keep us posted since this is completely new area and new approach for PC treatment - that is why there is so little information available.