Apple users may want to check the note taking, hierarchical tagging, page scraping and very hacker friendly iOS and macOS app Bear: https://bear.app. I'm a paying customer but there's also a free version.
They also have a new alpha with an improved editor https://bear.app/alpha/
* it uses a markdown like syntax
* all syntactic characters (bold, italic, headline, tags, ...) are always displayed and not converted to rich text format (such as Slack does) while still applying the visual formatting. Like in a code editor, I see all characters which I type
* its underlying SQLite database is documented so that you can integrate/automate to your desire: https://bear.app/faq/Where%20are%20Bear's%20notes%20located/