Is brute-forcing a 1M token context window the right approach?

I am trying to query and extract information from a large, semi-structured org-mode file (with hierarchical entries and cross links) of about 800000 tokens length (depending on LLM, file size is about 2.5MB). This is basically a notes file spanning about 10 years of practical information of various kind, and definitively way too long to remember what's all inside. The file cross-references also elements of a maildir directory with ca 100000 mails.