There are many opinions here that are rather do not follow your idea as-is, but I would like to say do not give up if your project is even dedicated for only yo

There are many opinions here that are rather do not follow your idea as-is, but I would like to say do not give up if your project is even dedicated for only your use-case. I believe, you already know the way how you write data is exactly what s-expressions in Lisp/Scheme languages are. I have been working in an editor, which has similar syntax but is really dedicated to create easy A4/letter paper print-outs instead of just typical documents. It is really works nice and if you will come with tooling (editor, components, mixins), very low/gradual learning and good execution you might cut out some market share if you will target specific niche if you already know. About the syntax and tooling - if you target typical user who already knows Word or Markdown, you should also try out to resemble the "actions" they typically would do. I mean, if I would need to create a list item, I think I will support the hyphens or star notation. They are kind of an idiom of a list item already. The same fact is that you can think out of competing with LaTeX in terms of typesetting, pdf rendering, ease of embedding graphs or being a Jupyter notebook/orgmode competitor in terms of running inlined code (i.e. code block), out-of-the-box layout formatting (report, 2-columns, article) etc. etc.