I use org mode. It's actually why I started using emacs (spacemacs specifically).

I have a notes folder. Everything goes in there.

I have a raw.org file and a notes/raw directory. This is where I put downloads (videos/etc) and notes on that content. These notes are unsynthesized but tagged by content (e.g. dev, python, architecture).

I periodically review recent notes and pull out the especially useful data into more synthesized files, such as python.org.

I also maintain a couple "log" files, called worklog.org and devlog.org. This is what I use as a scratchpad for work and personal dev respectively. Each day gets an entry in the file.

I have an inbox.org file which is where I add a TODO for anything I might want to do, such as 'read this article in the future'. I don't really move stuff out of it though - I just mark it as done when I do it. Things get tagged here too, so if I feel like learning something about elixir, I can just look in inbox.org for a TODO tagged elixir.

I also have a comprehensive "learn" directory that lives outside my notes folder. This is where any notes or learning based activities that requires source files goes. That is organized primarily by tech, then has folders such as "examples", "basics", and "workbook". Workbook is where I store notes and code related to going through longer tutorials or books. So for example, I've been going through elixir recently: I have a folder at learn/elixir/workbook/getting-started for going through this: https://elixir-lang.org/getting-started/introduction.html

I'm not completely happy with how the learn directory works out - it kinda fragments the structure of my notes. But it's the best way for me I've tried.