Juhyeok Kim11 downloadsPreview rendered Markdown at the cursor while writing in Source mode.

Markdown is easiest to control when its syntax stays visible. Markdown Lens keeps Source mode as the main workspace and opens a small rendered view around the cursor—without switching modes or hiding the source.
Enable the plugin, switch a note to Source mode, and place the cursor in the text. Lens width, visible lines, and font size can be adjusted in the plugin settings.
Until it reaches the Community directory, install it with BRAT from https://github.com/philaxis/markdown-lens.
Desktop only. No account, ads, or telemetry; note content is not transmitted. Closed source; personal and internal business use is allowed under the commercial license.