The reason people use Electron in the first place is that they wanna share a codebase between web, desktop and possibly mobile.
While Flutter can technically do that, the web apps it outputs are atrocious with poor usability and accessibility. It’s drawing the whole UI on a canvas element which causes all kinds of issues.
I get the point here but I think it’s the wrong approach. If you feel the email needs too much business fluff, just write it more casual and get to the point quicker.