1. Install CoC
2. Install zig.vim
3. Install jsonc.vim (optional, so that comments in json are not highlighted as errors)
4. place the following snippet in your coc-settings.json (open it using :CocConfig)
5. place the following snippet in your init.lua / init.vim / .vimrc

// coc-settings.json
{
  // All nested settings will only affect Zig files.
  "[zig]": {
    // enable format-on-save from CoC + ZLS
    //
    // Formatting with ZLS matches `zig fmt`.
    // The Zig FAQ answers some questions about `zig fmt`:
    // https://github.com/ziglang/zig/wiki/FAQ
    "coc.preferences.formatOnSave": true,

    // Show inlay hints in the editor. Inlay hints are short annotations within the code,
    // which show variable types or parameter names.
    // "inlayHint.enable": true,
    
    // Use the language server to perform code highlighting
    "semanticTokens.enable": true
  },

  "languageserver": {
    "zls": {
      // use `"command": "zls"` if `zls` is in your PATH
      "command": "/path/to/zls_executable",
      "filetypes": [ "zig", "zon" ],
      // There are two ways to set config options:
      //   - edit your `zls.json` that applies to any editor that uses ZLS
      //   - set in-editor config options with the `settings` field below.
      //
      // Further information on how to configure ZLS:
      // https://zigtools.org/zls/configure/
      "settings": {
        // Whether to enable build-on-save diagnostics
        //
        // Further information about build-on save:
        // https://zigtools.org/zls/guides/build-on-save/
        // "zls.enable_build_on_save": true,

        // omit the following line if `zig` is in your PATH
        "zls.zig_exe_path": "/path/to/zig_executable"
      }
    }
  }
}

-- init.lua

-- don't show parse errors in a separate window
vim.g.zig_fmt_parse_errors = 0
-- disable format-on-save from `ziglang/zig.vim`
vim.g.zig_fmt_autosave = 0

" init.vim or .vimrc

" don't show parse errors in a separate window
let g:zig_fmt_parse_errors = 0
" disable format-on-save from `ziglang/zig.vim`
let g:zig_fmt_autosave = 0

Code Actions on save

source.fixAll

vim.api.nvim_create_autocmd('BufWritePre',{
  pattern = {"*.zig", "*.zon"},
  command = "call CocActionAsync('fixAll')"
})

autocmd BufWritePre *.zig,*.zon call CocActionAsync('fixAll')

source.organizeImports

vim.api.nvim_create_autocmd('BufWritePre',{
  pattern = {"*.zig", "*.zon"},
  command = "call CocActionAsync('organizeImport')"
})

autocmd BufWritePre *.zig,*.zon call CocActionAsync('organizeImport')