I happily paid money for Typora, which does roughly the same thing for just Markdown without support for JSON, Yaml (that I know of). This feels like a ripe space, especially with LLMs eagerly outputting reams of parseable text with embedded diagrams.
The price of a fancy burger doesn't seem all that unreasonable for a piece of software one finds even moderately useful (of course, depending on your local exchange rate that may be more or less true)
Thanks! Typora is great - Ferrite aims for similar polish but with native Mermaid, structured data support (JSON/YAML/TOML tree viewer), and the pipeline feature for shell integration. And it's open source!