That's why I'm working on a local-first with native-like performance Notion alternative using Qt C++ and QML called Plume[1]. It uses an advanced block editor[2] that I built from scratch. All notes are simply plaintext/markdown underneath. Advanced blocks (like Kanban, for example) uses very simple syntax, for example:

  {{kanban}}
  # Todo  
  - [ ] item 1
  - [ ] item 2
  # In Progress
  - [ ] item 1
  - [ ] item 2
  {{/kanban}}

[1] https://www.get-plume.com/

[2] https://imgur.com/NIgDLOU