I really wish I could move to those nice new editors, but as a vim user I just feel paralyzed when I cannot use vim bindings. And all "emulations" I tried are just incomplete.
as an avid vim user who moved to emacs evil-mode for a better vim than vim, and now who uses vscode with vscode-vim, it pains me to admit a web browser based editor is a better vim than vim. Somehow starts faster and is less kludgey and more scriptable. You can install extensions on phoenix.new, so vim is not a blocker for you. I drive vim emulation in it every day both on desktop app and within phoenix.new. Couldn't use it without it :)