Copy from VSTS Git Repository to public Gist. It does not complete to copy ...

copy-vsts2gist.ps1

# Requires -Version 4.0
# {account} is VSTS account name
# {repositoryName} is VSTS Git Repository Name
# {GitHubAccount} is GitHub Account name
$vstshost = 'https://{account}.visualstudio.com/Private/_apis/git/repositories/{repositoryName}/'

#GitHub PAT
$tokenGitHub = ''
$Base64TokenGitHub = [System.Convert]::ToBase64String([char[]]$tokenGitHub);
$headersGitHub = @{
    Autorization = 'Basic {0}' -f $Base64TokenGitHub;
};

$gists = Invoke-RestMethod -Headers $headersGitHub  -Method Get -uri 'https://api.github.com/users/{GitHubAccount}/gists'

#VSTS PAT
$TokenVSTS = ''
$authVSTS =  ("{0}:{1}" -f '{VSTSUserName}',$TokenVSTS)
$Base64TokenVSTS = [System.Convert]::ToBase64String([char[]]$authVSTS);
$headersVSTS = @{
    Autorization = 'Basic {0}' -f $Base64TokenVSTS;
};

$base64AuthInfo = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f '{VSTSUserName}', $TokenVSTS)))
$vstsuri = $vstshost + 'commits?api-version=1.0'
#get recent commits
$result = Invoke-RestMethod -Uri $vstsuri -Method Get -ContentType "application/json" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}

#get commit detail
$vstsuri = $result[0].value[0].url
$result = Invoke-RestMethod -Uri $vstsuri -Method Get -ContentType "application/json" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}

#get change files
$vstsuri = $result._links.changes.href
$result = Invoke-RestMethod -Uri $vstsuri -Method Get -ContentType "application/json" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}

#action is add or modify?
foreach($commit in $result.changes){
  $vstsfile = $commit.item.path.substring(1)
  foreach($gist in $gists){
    foreach($gistfile in $gist.files){
      $gistfile = $gistfile | Get-Member -MemberType NoteProperty | select Name
      if($gistfile.Name -eq $vstsfile){
        if($commit.changetype -eq "edit") {
        }
        $target = $gist
        break;
      }
    }
  }
#these codes under constraction...
  if($target -eq $null){
    if($commit.changetype -eq "add"){
      $vstsuri = $vstshost + 'items?scopePath=' + $vstsfile + '&api-version=1.0'
      $result = Invoke-RestMethod -Uri $vstsuri -Method Get -ContentType "application/octet-stream" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}
      $gists = Invoke-RestMethod -Headers $headersGitHub  -Method post -uri 'https://api.github.com/users/{GitHubAccount}/gists'
    }
  }
}

#these codes under constraction...
$commitresult = Invoke-RestMethod -Uri $commituri -Method Get -ContentType "application/json" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}