Thanks for your suggestion. I tried peek.nvim and found some cons:
- It required Deno runtime
- It does not support Table of Contents
- It does not have Dark/Bright mode button
- It does not support PlantUML
- It does not support term definition
- It does not support Sequence Diagrams
- It does not support Flowcharts
- It does not support Graphvis Dot
- It does not support Charts
- It does not support local images
