evil

Evil is the extensible vi layer for Emacs, and it is the reason a lot of Vim users can stomach Emacs at all. It brings real modal editing, normal mode, visual mode, operators, text objects, the muscle memory you already have, into Emacs without the half-measures other emulations settle for. It is thorough enough that most people forget they are not in actual Vim.

There is nothing to host and nothing to pay. It is a GPL-licensed Emacs package you install through MELPA in a couple of lines. The reason you would bother: Emacs has decades of extensibility, Org mode, Magit, a built-in Lisp machine, that no Vim setup matches, and Evil lets you keep your editing keys while you get all of it. Distributions like Doom and Spacemacs are built on top of it.

If you are a Vim user curious about Emacs, this is the on-ramp. If you are an Emacs user who never clicked with the default keybindings, this is the fix. Either way it costs nothing and you can back out anytime.

The catch is the seam. Evil is excellent, but Emacs packages are written assuming Emacs keybindings, so you will occasionally hit a mode where Evil's bindings and a package's bindings fight. The community has shims for the big ones, evil-collection covers a lot, but expect to tune your config rather than have everything work on the first launch.