onivim also seperated the core functionality of the vim editor into a seperate library libvim , this would have been great for other people looking to make their own gui frontend to vim .

neovim does not give a libneovim, but exposes an rpc where you communicate with neovim running as another process, this I would have thought have more latency but apparently is fast enough , this is how the vscode plugin for neovim is able to provide a near complete vim experience. Other neovim guis like neovide use this too