How to include Source Branch name or pull request ID in ADO release title?

I have a CD release pipeline which gets deployed whenever new Pull Request (PR) build is succeeded. I want to include the source branch name of that PR as well as PR id in my release title.

I tried below variables in title, but they didn't work:

$(system.pullRequest.sourceBranch)

$(BUILD.PullRequest.SourceBranch)

$(BUILD.PullRequest.ID)

I just don't want to use $(Build.SourceBranch) or $(Build.SourceBranchName) as it doesn't give me expected value.

My expected release title: "PR Run- personal/ak/randombuild with PRID 1234 - 01"

PR variables are not available in the release scope: How do I manage the names for new releases?

However,. you can use BuildId to get the detailed build information via Rest API and update your release name.

The PowerShell example:

$user = ""
$token = $env:SYSTEM_ACCESSTOKEN

$base64AuthInfo = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f $user,$token)))
$orgUrl = "$env:SYSTEM_TEAMFOUNDATIONCOLLECTIONURI"
$teamProject = "$env:SYSTEM_TEAMPROJECT"
$currentBuildId = "$env:BUILD_BUILDID"

$restApiGetBuild = "$orgUrl/$teamProject/_apis/build/builds/$currentBuildId`?api-version=6.0"

function InvokeGetRequest ($GetUrl)
{   
    return Invoke-RestMethod -Uri $GetUrl -Method Get -ContentType "application/json" -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)}
}

$resBuild = InvokeGetRequest $restApiGetBuild

if (-not [string]::IsNullOrEmpty($resBuild.triggerInfo.'pr.number'))
{
    Write-Host "##vso[release.updatereleasename]PR Run - PR ID" $resBuild.triggerInfo.'pr.number'
}

Add that as a step in the release. The result:

Do not forget to provide access to the token for your release pipeline: