Most dedicated markdown editors all end up using the same JS code editor components like Ace, CodeMirror or Monaco, and those editors have great vim keybindings

Most dedicated markdown editors all end up using the same JS code editor components like Ace, CodeMirror or Monaco, and those editors have great vim keybindings usually as extensions or options. See if the tool you're using lets you flip those vim bindings on. For some editors they expose it as an option and for others you have to hack around with the source (for example enabling it with stackedit, a PWA markdown editor like ghostwriter, is possible with some hacking: https://github.com/benweet/stackedit/issues/254 https://github.com/benweet/stackedit/issues/254 ).