Current Version:
function setAutoLogon($username,$password){
    $regWinlogon='REGISTRY::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon'
    $regKeyUsername='DefaultUserName'
    $regKeyPassword='DefaultPassword'
    $kegKeyAutologin='AutoAdminLogon'
    $regKeyDefaultDomain='DefaultDomain'
    function testCredential($username,$password){
        # Get current domain using logged-on user's credentials
        $isDomainJoined=$env:USERDOMAIN -ne $env:COMPUTERNAME 
        if($isDomainJoined){
            $domain="LDAP://"+([ADSI]"").distinguishedName # Legacy method without importing ActiveDirectory module
            $login=New-Object System.DirectoryServices.DirectoryEntry($domain,$username,$password)
            try{
                if($null -ne $login.name) {
                    write-host "$username credential is valid" -foregroundcolor green
                    return $true
                }else{
                    write-warning "invalid credentials"
                    return $false
                    }
            }catch{
                write-warning $_
                return $false
                }
        }else{
            if(!(get-command psexec.exe)){
                [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
                if (!(Get-Command choco.exe -ErrorAction SilentlyContinue)) {
                    Set-ExecutionPolicy Bypass -Scope Process -Force; iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))
                    }
                $null=choco install sysinternals -y
            }
            $pinfo = New-Object System.Diagnostics.ProcessStartInfo
            $pinfo.FileName = "psexec.exe"
            $pinfo.RedirectStandardError = $true
            $pinfo.RedirectStandardOutput = $true
            $pinfo.UseShellExecute = $false
            $pinfo.Arguments = "\\$env:computername -u $username -p $password -s cmd /c hostname"
            $p = New-Object System.Diagnostics.Process
            $p.StartInfo = $pinfo
            $p.Start() | Out-Null
            $p.WaitForExit()
            if($p.ExitCode -eq 0){
                return $true
            }else{
                return $false
            }
        }
    }
    
    $isDomainJoined=$env:USERDOMAIN -ne $env:COMPUTERNAME
    $isPasswordValid=testCredential $username $password
    if($isPasswordValid){
        Set-ItemProperty -Path $regWinlogon -Name $regKeyUsername -Value $username
        Set-ItemProperty -Path $regWinlogon -Name $regKeyPassword -Value $password
        Set-ItemProperty -Path $regWinlogon -Name $kegKeyAutologin -Value 1
        if($isDomainJoined){
            Set-ItemProperty -Path $regWinlogon -Name $regKeyDefaultDomain -Value $env:USERDOMAIN
        }
        write-host "$env:computername has been set for auto-logon with account $username" -ForegroundColor Green
        write-host "Please reboot for changes to take effect."
    }else{
        write-warning "Provided password is invalid for account $username"
    }
}
Old batch commands:
# set /p password="Enter password for %USERNAME%: " 
# reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v DefaultUserName /t REG_SZ /d %USERNAME% /f
# reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v DefaultPassword /t REG_SZ /d %password% /f
# reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v AutoAdminLogon  /t REG_SZ /d         1  /f