I don't know much about Gemini beyond a cursory look, but I don't think inline media is impossible. IIUC it is up to the Gemini client to decide if it displays media inline.

My understanding is that Gemini clients don't display inline media in order to defeat privacy-compromising techniques such as tracking pixels. A Gemini client could very reasonably decide to show images inline if they are larger than 16x16 for instance.