wingetCompleter.ps1

$wingetCompleter = {
    param($wordToComplete, $commandAst, $cursorPosition)

    $tokens = $commandAst.Extent.Text.Trim() -split '\s+'
    $completions = switch ($tokens[1]) {
        'install'  { "-q","-m","-v","-s","-e","-i","-h","-o","-l",
                     "--query","--manifest","--id","--name","--moniker","--version","--source","--exact","--interactive",
                     "--silent","--log","--override","--location","--help"; break }
        'search'   { "-q","-s","-n","-e","-?",
                     "--query","--id","--name","--moniker","--tag","--command","--source","--count","--exact","--help"
                     break }
        'show'     { "-q","-m","-v","-s","-e","-?",
                     "--query","--manifest","--id","--name","--moniker","--version","--source","--exact","--versions","--help"
                     break }
        'source'   { $srcCommands = "add","list","update","remove","reset"
                     if (($tokens.Count -ge 3) -and ($srcCommands -contains $tokens[2])) {
                         switch -regex ($tokens[2]) {
                             'add'                { "-n","-a","-t","-?","--name","--arg","--type","--help"; break }
                             'list|update|remove' { "-n",,"-?","--name","--force","--help"; break }
                             'reset'              { "-n",,"-?","--name","--help"; break }
                         }
                     }
                     else {
                         $srcCommands + @("-?","--help")
                     }
                     break
                   }
        'hash'     { "-f","-m","-?","--file","--msix","--help"; break }
        'validate' { "-?","--manifest","--help"; break }

        default { "install","show","source","search","hash","validate","-v","--help","--info","--version" }
    }

    $completions | Where-Object {$_ -like "${wordToComplete}*"} | ForEach-Object {
        [System.Management.Automation.CompletionResult]::new($_, $_, 'ParameterValue', $_)
    }
}

Register-ArgumentCompleter -CommandName winget -Native -ScriptBlock $wingetCompleter

Please consider upvoting this winget-cli issue: microsoft/winget-cli#331