FZF + ripgrep is really killer for me. I don't even bother organizing my notes anymore, I just throw everything markdown files in a flat directory and then I have a script that uses FZF + ripgrep to search through it when I need it. I search by "last modified first" so unless I'm digging for something very old the results are instant. Code snippets, finances, TODO lists, cake recipes... It's all in there.
I use the same system in Vim to browse source code. It's very powerful, very fast, works with any language and requires zero configuration.
You'll need to set NOTES_DIR in your environment to wherever you want your notes to be stored. Then you can write `note something` to create or open $NOTES_DIR/something.md with your $EDITOR.
If you type "note" without parameter you'll start a search on all the note names, ordered by last use. If you type "note -f" it starts a full text search.
For best results you should have the fzf.vim's preview.sh somewhere in your fs, otherwise it'll use "cat" but it won't be as good looking (see FZF_PREVIEW in the script).
Hopefully despite being shell it should be readable enough to tweak to your liking.
Note that it was written and used exclusively on Linux, but I did try to avoid GNU-isms so hopefully it should work on BSDs and maybe even on MacOS with a bit of luck.
I use the same system in Vim to browse source code. It's very powerful, very fast, works with any language and requires zero configuration.