I can’t even find results for the last two tiers on google but I"d relly want to know more.

MS OneNote is my preferred tool for this as you habe an infinite notebook and can doodle anywhere on its infinite pages. I usually have a chapter for rules, NPCs, Fluff (locations and past events), PCs (their history and plot hooks), with pages for e.g. combat rules, 1 page per NPCharacter etc. You can import pictures (and also paste them directly from ON to Discord) and share the notebook (or single pages) with others online.