Gemini's text specification is kind of a subset of Markdown -- it supports three levels of headings, block quotes, bulleted (but not numbered) lists, preformatted text, and links (but not inline links).

While I'm a fan of richer text styling -- I'm often the dingus on HN being downvoted for suggesting that web fonts are not an intrinsically bad thing -- I think Gemini is mostly just fine the way it is. The thing that's kind of a blocker for me is, of all things, no way to emphasize inline text. Changing text from regular to italic/oblique carries semantic meaning. If you could mark it with _underlines_ like Markdown, for instance, it could be just like some of the other Gemini text that's described as "strictly optional for clients to do anything special with".