How to reference PHP Variables

I can see some $_SERVER globals in the action steps area but wondered how I could reference said variable. For example, we have a third party solution handling single sign-on which saves a variable as ‘$_SERVER[‘OIDC_CLAIM_first_name’]’. If I echo this back on a standard PHP page I see my name printed. However, adding an echo to Wappler produces no result. My plan is to use such variables as part of database queries for roles etc if only I knew how to access them correctly

I suspect I am missing something obvious so any pointers appreciated.

Thanks and best regards,
Brian