It's a possibility but I'm not using those myself so I don't have good intuition on what is a good UI for that.
A relatively simple thing would be to add "preview block" which e.g. for mermaid blocks would add a panel with rendered diagram.
A much more complicated solution would be to add codemirror view which renders diagram when cursor is outside the markup and switches to editing when inside markup.
For equations and flowcharts, I would argue that the rendering is more important than the textual "code", so a "preview block" with rendered output would be very useful already.
A much better UI would be something like what you described, such as
A relatively simple thing would be to add "preview block" which e.g. for mermaid blocks would add a panel with rendered diagram.
A much more complicated solution would be to add codemirror view which renders diagram when cursor is outside the markup and switches to editing when inside markup.
But that's significantly more complicated.