Hey, I was an engineer on the VS Code team. I just looked at your vsix and it looks really well architected.
This is a WYSISYG so you can edit and not just preview the rendered markdown. So it works almost like MS Word for Markdown files.
The preview works fine but any attempt to edit a file with 1.133.0 results in an extension crash. I'll submit a bug report.
Sounds good and thanks for the feedback. Feel free to submit an issue on the git repo with your bug report.