Getting `bContext` from `Main`

I’m trying to wrap my head around Blender development, so I’m attempting, showing geo node error messages in the info editor. The plan is to use CTX_wm_reports() to get the report list in order to add the error message (not my plan, see the task linked above). That function takes a bContext. So far, I’ve figured out that I can use DEG_get_bmain() to get a pointer to bMain, but I’m unsure where to go from here to get the context I need?