https://github.com/CTRL-Neo-Studios/vertex
I've always been fascinated with the UX of Obsidian's markdown editor and are very fond of it. However, other pre-existing rich-text editors doesn't provide the same WYSIWYG experience as Obsidian's - I don't know the right word to say it but I feel that "they aren't flexible enough for users to edit the source and view the rich-text."
So with the help of LLMs I've managed to come close to making an editor component that has somewhat good-enough UX close to Obsidian's based off of CodeMirror 6, and I extended that effort further into attempting to recreate Obsidian - which then became Vertex.
The current license is probably temporary as I've heard AGPL or GPL licenses are "toxic"(?) but that will change in the future probably to MIT or something else, like the editor component's license. But for the current state of the app, AGPL v3 seems fine for me.
The current state of the Markdown Editor app is in alpha, with two main modes: the Workspace mode and Single-space mode; the Workspace is the closest to Obsidian's UX in Vault editing, where Single-space is more for a convenient, quick single-file editing. There isn't an actual alpha build release yet, but you can clone and build it yourself from the source using bun. (See readme.md)
Currently I use a build of it myself and by far in terms of single-file editing experiences it had worked great.