That said, I actually don't think the integrated Overleaf editor is bad. They have Vim keystroke support, so I can fairly easily use it without much trouble on my end.
I’m not comfortable using it for extended work though. I miss things like surround text objects for TeX environments and macros (provided by evil-tex or vimtex), ergonomic entry of equations (provided by CDLaTeX or by the vimtex insert-mode bindings), autoformatting (provided by latexindent), and some navigational abilities (e.g. being able to jump to the documentation of TeX packages with a single keybinding). On top of that, there’s the missing general editor plugins… And at least on MacOS, their PDF viewer is quite blurry compared to the native viewers :)
With that said, I think Overleaf is great, and it’s made LaTeX itself much more accessible for a wider audience. But for me, it pales in comparison to a local Emacs or Vim configuration…