You really need to give this a go so we can give more targeted advice, but I can give you some high level guidelines. First, you need to review the QnA Maker Programmatic APIs. These should allow you to access all of the functions you require. You can use a number of different tasks in DevOps Release Pipeline to call these, but I prefer Azure CLI for reasons I mention below.
With the API alone, you would need to hard code in values such as your subscription key, KBID, etc. To avoid hard coding these values, you can get them programmatically as well via the Azure CLI. If you set task version to 2.X, you can use PowerShell. Here is my script to get the QnA Maker key, subscription key, KBID, and Endpoint Key.
$QNAKEY= & az cognitiveservices account keys list -g "YOUR_RESOURCE_GROUP" --name "YOUR_COGNITIVE_SERVICE" --query key1 -o tsv
$header = @{"Ocp-Apim-Subscription-Key"="$QNAKEY"}
$res = Invoke-RestMethod -Uri "https://westus.api.cognitive.microsoft.com/qnamaker/v4.0/knowledgebases" -Method 'Get' -Headers $header
$kb = $res.knowledgebases | Where-Object name -eq "YOUR_KB_NAME"
$kbId = $kb.id
$res = Invoke-RestMethod -Uri "https://westus.api.cognitive.microsoft.com/qnamaker/v4.0/endpointkeys" -Method "Get" -Headers $header
$endpointKey = $res.primaryEndpointKey
Note the above is assuming you have the KB created already. Just take a look at the import API call and see what you need and adjust accordingly. Do note that if you are creating a new KB, QnA Maker does not ensure uniqueness of the KB name. Without some sort of check, you will end up creating duplicate KBs.
You should be able to use these methods (QnA Maker API and Azure CLI to call it within pipelines) to access any feature of KB management you need.