Deploy only the deltas

sfRelease.ps1

#Azure DevOps / Powershell example
$priorVersionNumber = $args[0] #Assumption: you have the version number the prior deployment to this environment was tagged with
$newVersionNumber = $args[1] #Assumption: you have the new version number to tag the new commit with
$environment = $args[2] #Assumption: you have the name of the environment you are deploying to
$releaseCommit = $args[3] #Assumption: you have the id of the commit you are deploying

Invoke-Expression "git checkout $releaseCommit"

#Use the SFDX Git Delta plugin to deploy the delta between the checked out release commit and the tag last deployed to the current environment
#https://www.npmjs.com/package/sfdx-git-delta
$deploymentResponse = Invoke-Expression "sfdx sgd:source:delta --to HEAD --from $priorVersionNumber --output . --loglevel ERROR"

#tag and update variable if deployment was successful
if($deploymentResponse -eq $null) {
  Invoke-Expression "git tag -a $newVersionNumber"

  #Azure DevOps Example - update your variable group to indicate the latest version / tag that was deployed to the environment
  Invoke-Expression "az pipelines variable-group variable update --group-id sfRelease --name $environment --value $newVersionNumber"
}