Maybe I'm misunderstanding, but there is literally a Share button in Canvas right below each response with the option to export to Docs. Within Docs, you can also click on the Gemini "star" at the upper right to get a prompt and then also export into the open document. Note that this is a with "experimental" Gemini 2.5 Pro.

Docs supports markdown in comments, where it's the only way to get formatting.

I love Googles product dysfunction sometimes :/