UpNote. I use it like a combination of the gollum wiki described by OP, but I just put everything in there. I have watch and reading lists for things I want to check out, writing projects, notes for TTRPG games, I keep extensive notes on healthcare-related stuff, and so on. I like UpNote because it's lightweight, has windows, linux, and android apps, and because it has a one-time $25 lifetime membership that does free syncing forever instead of a monthly subscription like most other things seem to. I've tried OneNote, Evernote, Obsidian, Joplin, AnyType, and a bunch of others and didn't like them for various reasons, but UpNote is both pretty small and also has a pretty full-featured editor that can do rich text, all kinds of formatting, media files, etc.
The only thing I've run into that UpNote wasn't ideal for is I started writing a novel a couple months ago and managing the structure and notes and all that got a little unwieldy so I picked up Scrivener. Still wish they had an updated linux client or there was some good, complete, feature-rich linux-native equivalent, but it runs pretty good under wine, so.